I was raised Catholic. There would be a reading from the old testament, a reading from the new testament, and then a reading from one of the four canonical gospels. The Priest would do a homily, usually re the readings, but now and then something else. There were also some hymns, reciting the creed and communion. Finally a blessing and you were out the door, unless you skipped out after communion - which was bad because you missed the most important part of the mass, the blessing, and you had to go the whole next week unblessed.
As an adult I have attended Unitarian services. This can vary from congregation to congregation but it is basically a gathering song, then the sharing of joys and concerns. (at this point kids head to RE) A reading, often secular or from any religious tradition. Then some more singing and then a Sermon (Rev Dan in Elgin, IL was an awesome sermon giver) that made you think about life and the world we live in. Maybe another song, then we'd all hold hands and recite the 7 principles. Then coffee and chatting.