When it comes to textbooks, what do they mean when they say that it is a 'brief' edition?

I'm looking for cheap textbooks. I kept putting in the ISBN number, and then I realized that was dumb. All I would get was the newest most expensive (even on sites like cheaptextbooks.com). So I started searching just by the title I found stuff really cheap, but it said brief edition. I figure the edition (especially on a spanish textbook) doesn't really matter. I just want to be sure I'm not getting like half of what I actually need. so my question is What does "Brief" Edition mean, on a textbook?|||short edition|||It's just like what's in it and gives you an overview. It doesn't contain everything