The United States Conference of Catholic Bishops (USCCB) defines liturgy as "the general term for all the church's official acts of worship". These types of worship include the Mass, sacraments (such as baptism), and the Liturgy of the Hours (which are special prayers said by clergy/religious).
According to the Catechism of the Catholic Church, the Sacraments are "signs of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us" (CCC, 1131). In other words, the Sacraments that we receive as Catholics give us the grace we need to live out our faith and obtain the eternal life that has been promised to us.