SN, you didn't ask about Church of Christ but I will volunteer this one. I am not a member of the C of C, but I have many close relatives who are. Besides JSM17 won't provide an answer because he doesn't believe the C of C is a denomination. Rather, he believes it is the only true church, i.e., the only church that is true to the New Testament. However, if I make a mistake here, he will probably jump in and correct it. :thumbs:
Baptism. The C of C administers baptism only to believers and only by immersion. The minister (what they call the pastor) and elders are qualified to baptize. There may be other men qualified to do this as well but I can't say for sure. They have a somewhat sacramental view of baptism, but deny any belief in sacraments. Rather, they believe baptism is necessary for salvation because we are told in the N.T. to be baptized. If we do not obey the scriptures, we are not saved. Obedience is a word you will hear often among C of C people.
Communion. Communion is observed every Sunday without exception. The bread is passed through the congregation, just as Baptists do. The cup (individual small containers of grape juice) is then passed. However, in the C of C, when one takes a piece of bread or a cup of juice, he or she eats or drinks it immediately. There is no waiting for the entire congration to be served and no statement by the minister such as, "This is my body that is broken for you, do this in memory of me." They reject the concepts of transubstantiation and consubstantiation. They reject the idea that communion is a sacrafice. Rather, they "do it in memory of Me." They also do it in obedience to Christ's command. I would assume they practice open communion because I have visited them many times, it was always offered to me, and I have always received it. However, I doubt that you would find this in all congregations.
Calvinism is not even remotely related to C of C beliefs. They don't even talk about it but if they did, it would be to spurn the very idea.
Once saved always saved, like Calvinism, is not even on their radar. I think you would find complete unanimity in the belief that Christians can fall from grace and be completely lost.
Different views. Different views are held but they aren't as wide as the differing views of Baptists. I think you will mostly find some C of C people who are willing to cooperate and fellowship with other churches while others refuse to do so. Another area where you will find differences is music. Some Churches of Christ will permit musical instruments for weddings. Others will not all a musical instrument in the building. They all agree that musical instruments should not be a part of Christian worship.