How do Roman Catholics distinguish the Mass from Holy Communion?

The Roman Catholic Church distinguishes between the Mass and Holy Communion by identifying them as two aspects of the same sacrament: the Eucharist. In this theological framework, the Church defines the Eucharist as both a sacrifice and a sacrament.1

• The Mass as Sacrifice: The Mass is the central act of worship, understood as a memorial and a sacrifice. It makes present the sacrifice of Jesus Christ on the cross in an unbloody manner. During the liturgy of the Eucharist, the priest consecrates the bread and wine, which, through transubstantiation, become the real presence of Christ’s body and blood.231
• Holy Communion as Sacrament: Holy Communion is the act of receiving these consecrated elements. By partaking in this sacred meal, members of the church enter into intimate fellowship with Christ and one another, receiving spiritual nourishment and strengthening their unity as a community.21

Essentially, the Mass is the entire liturgical service that culminates in the celebration of the Eucharist, while Holy Communion is the specific act of receiving the consecrated bread and wine within that rite.231