What is the difference between an Evangelical and a Southern Baptist, if any?

The Southern Baptist Convention is the largest Protestant denomination in the world, and many if not most of its members could probably be called "evangelical" in their religious practice; the conference is commonly referred to as an Evangelical Christian denomination.

"Evangelical" in this context refers to a collection of theological beliefs including the necessity of personal conversion, authority of the Bible, and the application of Christianity to political and social issues.

So, in answer to your question, most Southern Baptists are Evangelical, and a plurality of American Evangelicals are Southern Baptists, but they are not really the same thing. "Southern Baptist" refers to membership in a specific church; "Evangelical" refers to an outlook on life that can be found to varying degrees in most Christian churches, but more so among Baptists, Evangelical Free, and Assembly of God churches, than others.

https://en.wikipedia.org/wiki/Southern_baptist
https://en.wikipedia.org/wiki/Evangelicalism