Catholicism is a sect of Christianity, so there are many similarities between Catholicism and other sects, but also many differences regarding the history of the church and beliefs. Catholics believe that Jesus named his apostle, Peter, as his successor and head of church and they follow papal law.
Other sects of Christianity do not believe that Peter was appointed head of the church by Jesus or that Jesus ever established a church. The establishment of the church is important because it is through the succession of Peter that the pope has authority. Catholics believe that God speaks through the Pope on matters of dogma.
Catholics have a tradition of an all male priesthood who are not allowed to marry, while many other sects allow for female ministers and also allow priests to marry. Catholics do not follow the teachings of the Gnostic gospels like many other Christians do; instead, they follow their Sacred Traditions, which are believed to have been handed down by the authority of the Roman Catholic Church. Catholics often hold much more formal services than over Christians, in which the Liturgy is the most important part of Mass. Catholics also take part in the Eucharist, a tradition that many other Christians forgo.