Sister vs. Nun - What's the Difference?

African Sisters Education Collaborative (ASEC)

Left: A Catholic sister in Kenya, Africa helps to deliver a baby at her congregation's hospital. Right: Villanova basketball star Shelly Pennefather left her family, friends and basketball career to become a cloistered nun.

It’s true that the words “sister” and “nun” are used interchangeably to describe women religious in the Catholic church, but there are several differences in the lifestyle, ministry and vows of nuns vs. apostolic women religious.

The words “sister” and “nun” are used interchangeably in common speech, even amongst sisters, to describe women religious in the Catholic church. "Sister" is an all-encompassing term that applies to anyone any woman who takes vows in a religious order (including nuns). The distinction actually comes between the "nun" and "apostolic women religious".

The term 'apostolic women religious' is quite a mouthful and one rarely hears it in common usage. It's a technical term. Throughout this article we will distinguish the technical differences in canon law between sisters who take solemn vows (nuns) and sisters simple vows (all other sisters).

There are several important differences in the lifestyle, ministry and vows of sisters, namely between apostolic women religious vs. nuns. 

Nuns live, minister and pray within the enclosure of a monastery. Nuns also take solemn, perpetual vows publicly and give up all worldly goods including estates, endowments and inheritances. Nuns are devoted to a contemplative and cloistered life of meditation and prayer for the salvation of all.

All other sisters (or apostolic women religious), may live in a convent or even in their own apartment and can minister and work outside of their religious community. Sisters take simple vows in a public or private setting and these vows can be either temporary or perpetual. While sisters are able to own property or estates, they are not able to use or earn revenue from them. Sisters live an active vocation of both prayer and service, going to the people who need their service.

Lifestyle of a nun vs. lifestyle of a sister

The lifestyles of nuns and other sisters can be dramatically different. This is because of where they live and how they serve.  

Nuns live, work and pray in a convent or monastery

Prayer is their primary work of nuns. Nuns live what is referred to as cloistered (enclosed) or semi-cloistered life. They live, work and pray within the monastery or convent. Nuns are devoted to a contemplative life of meditation and prayer for the salvation of all. Most religious orders began like this. 

A nun’s vocation, or ministry, is to witness the primacy of prayer in the church, to serve as a reminder of the contemplative dimension in all lives and to intervene for others before God.

Many cloistered nuns only leave the enclosure for serious reasons and on rare occasions. So, it’s quite rare that you would meet a nun outside of the monastery or convent in the public eye. However, for some orders of nuns, the rules of enclosure are a bit more relaxed.

A few examples of congregations that live the cloistered lifestyle of a nun are: 

  • Carmelite Nuns
  • Poor Clares
  • Dominican Nuns
  • Visitandines
  • Holy Spirit Adoration Sisters
  • Handmaids of the Precious Blood
  • and many more

Learn more about the cloistered life of Catholic nuns

Apostolic sisters minister and work in the world

While prayer is a very important component of the lives of sisters, it is not their primary work. Apostolic sisters involve themselves in various kinds of employment that are helpful to humanity -- which is called ministry. The life of an apostolic sister combines a life of prayer with a life of active ministry. Many sisters’ ministries are determined by the needs of the poor and marginalized. 

The details of where a sister lives and how a sister serves in the world are determined by her particular religious order, or congregation. Some sisters live in convents while other sisters, because of the location of their ministry, may live in small groups in regular houses (usually rented) or on their own.

Even if a sister lives alone, she is still bound to keep in touch and be in relationship with the rest of the community, pray in union with the other sisters, attend meetings and be accountable in everything she does.

A few examples of congregations for Catholic sisters that live a life of ministry and prayer are:

  • Sisters, Servants of the Immaculate Heart of Mary
  • Sisters of St. Joseph
  • Sisters of St. Francis
  • Society of the Holy Child Jesus
  • Medical Missionaries of Mary
  • and many more.

Learn more about the life and ministry of Catholic sisters.

Solemn vows of nuns vs. simple vows of other sisters

Both nuns and sisters take vows of poverty, chastity and obedience, which are the three evangelical counsels or counsels of perfection in Christianity. As Jesus of Nazareth stated in the Canonical gospels, they are counsels for those who desire to become "perfect".

In Catholic canon law, a solemn vow is "a deliberate and free promise made to God about a possible and better good" that the Church has recognized as such.

The difference between a nun's vows and a sister's vows is the type that are taken and the setting in which the vows are taken. Nuns take what's called solemn vows, while sisters take simple vows.

Nuns take solemn vows in a public setting

The solemn vows of nuns are perpetual (not temporary) and are taken in a public setting. Nuns must give up all of their worldly possessions, including patrimony (property, estates, endowments and inheritances). Being released from solemn vows requires dispensation from Rome

Any other vow, public or private, individual or collective, concerned with an action or with abstaining from an action, is a simple vow. Even a vow accepted by a legitimate superior in the name of the Church (the definition of a "public vow") is a simple vow if the Church has not granted it recognition as a solemn vow.

Other sisters take simple vows in a public or private setting

The vows of sisters can be temporary or perpetual. Sisters take their simple vows publicly or privately. 

Sisters are permitted to retain their patrimony but must give up its use and any revenue.

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The meaning of "women religious"

The term, women religious, refers to women who have taken vows of chastity, poverty and obedience1 and who give their life to serve humanity. These women are also commonly known as sisters or nuns.

  • They belong to a religious institute established under Catholic Church Law.1
  • They endeavor to attain a common purpose by responding generously to the needs of humanity.
  • Provide meaningful services to all by inculcating holistic development regardless of religious affiliation.2

Despite their enormous contributions, there is little empirical research documenting the achievements of women religious in Africa or of the challenges they face. However, a case is made here that providing skills development for women in the sub-Saharan region might be a strategy for engendering change and development.3 Learn more about the work of ASEC.

Not all sisters are nuns

The most common misconception is that all sisters are nuns. This is not true. Both sisters and nuns are addressed as “sisters” which makes this confusing. 

For example, referring to a woman religious as Sr. Mary does not indicate whether or not Sr. Mary is a nun or a sister. But odds are, if you have met and spoken to Sr. Mary, she is a sister, not a nun. Most people won’t ever see or speak to a nun, because a nun lives and serves the majority of her life praying within the walls of the monastery. Most people will interact with apostolic women religious; the sisters who are serving within our community (like the sisters we had as teachers). 

As you can see, all women religious take the same vows of poverty, chastity and obedience. However, the vows differ between solemn and simple forms. Solemn vows are taken by nuns in a public setting and recognized by the church as solemn. Other sisters (apostolic women religious), take simple vows, which can be public or private. Simple vows refer to any vows not deemed solemn by the church. 

As you can see, there are several differences between nuns and other sisters. Women religious is a more encompassing term when referring to both sisters and nuns. However, all of these terms are used interchangeably and are socially acceptable to use.


  1. New Commentary on the Code of Canon Law by John P. Beal (607-709)
  2. The Encounter Between Christian and Traditional African Spiritualities in Malawi: The Search for a Contextual Lomwe Christian Spirituality by Francis G. Masuku
  3. Capacity Building: A Phenomenological Study of the African Women Perceptions and Experiences in the Leadership Training Program by Jane Wakahiu and Diane Keller

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Amy Fedele

Amy Fedele
Former ASEC Media & Communications Manager - USA  

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Sister vs. Nun - What's the Difference?