The only common denominator to the hundreds of Baptist groups is a rejection of infant baptism. Other than that, they are all over the map.
Perhaps the biggest division is that some are "free will" [Arminian] and some are Reform [Calvinist], but they differ in nearly all things. It is also the most divided group racially known to me in the USA, with some groups strongly African American and some nearly pure White.
Way back in my homeschool days, we worked closely with a Baptist School associated with a mega Baptist church. But that church could easily have been Presbyterian.... it was strongly Reformed, quoting Calvin all the time, had a hard time with Billy Graham and often mocked his "altar calls", and the worship service was quite traditional, formal and semi-liturgical... even the structure of the church was largely Presbyterian. The only thing I could see that made it "Baptist" was it refused to do baptisms for those under some magical and never disclosed age - oddly, it did not ask those so baptized to be re-baptized but it didn't do them. Since a lot of the school events happened during Sunday worship, I went to two or three services a year there.... the music was outstanding [and very traditional], the preaching very Protestant and well done. If Communion was ever celebrated, I never saw it [a point that struck me], but probably the single thing that struck me was no kids, they were all sent off to "Children's Church" so it was only adults in worship - which I just found odd.
I think nearly every belief and practice in Protestantism and beyond can be found in Baptist churches - just depends on WHICH Baptist church, but NONE of them has infant baptism: that's the common factor, it seems to me.
- Josiah