Hi Eric,
The difference between Seventh-day-Baptists and Seventh-day-Adventists is actually in the name. Seventh-day-Baptists also began in the 17th century while Seventh-day-Adventists began in the 19th century. However, the founder of the SDA (Seventh-day-Adventist) Church was a former Baptist preacher, so that is a little confusing. SDB (Seventh-day-Baptists) also believe the Bible is the only true Word of God and is the only authority for church teachings and doctrine. SDA get a lot of their teachings from their founders, especially Ellen G. White, who some consider a prophetess. Hope that cleared some things up!