Well, I can certainly say they don’t see eye to eye on a lot of things. A big difference is found between the Southern Baptist and American Baptist groups. Primitive Baptist is another group altogether.
The American Baptist churches, at least in our area, have been known to do Holy Union ceremonies for gay couples. That would not happen in a Southern Baptist church. The two American Baptist congregations with which I am familiar are also quite “high church” and liturgical, especially compared to most of the Southern Baptist ones in the area.
The Southern Baptist Convention was actually a lot more moderate until the early 1980s. I had a friend who was in a Southern Baptist seminary when the very conservative group took over.
The big thing you need to remember about Baptists is that they are basically diametrically opposed to Catholics in church organization. They have a strong tradition of the autonomy of individual congregations.