Members of female monastic orders are called nuns, and their vocation is to be the praying, beating heart of the Church at its centre. Unlike apostolic sisters, they do not serve manually within their communities, but their vocation is praying for the world from within the walls of their convent/monastery enclosure. Monastic communities usually carry out industrial work such as producing altar breads, liturgical garments, and religious artwork, amongst other trades.
Nuns are usually cloistered, meaning that they do not leave their convent/monastery apart from on rare occasions, for example for visits to the doctor. This frees them from worldly attachments and allows them to give themselves entirely to Christ, and this allows for a much deeper self-conversion than if they were to remain 'in the world'. For more information, head to cloisteredlife.com.
Monastic communities follow, and are defined by, a specific Rule, such as the Benedictines, who follow the Rule of Saint Benedict. Unlike apostolic orders, which can be much more varied and have broken off into many new sub-orders over time, many monastic orders still follow ways of life that have remained unchanged for hundreds of years.