rharv provided a good explanation of the differences.

My point of view.... Band In A Box (BB) is my writing tool. It's where I compose the song. I choose the key, the tempo, the style, the structure and work out the details for the finished song.

I save and close it then open Real Band (RB) and load that same file. I then add other parts that were not a part of the style in BB. For example a rock style fits well in today's country music but it doesn't have steel or fiddle or dobro. In RB I can easily add those and more to the song.

To me, they are similar but very different in how I use them. BB will not do what RB does and vice verse.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.