It's the same thing.
3 textures, each with it's own breaker. There are 3 sets of textures, each set has 2 textures that need to tile in every combination you put them (horizontally).
So... in the end you'll have 6 textures that are in pairs of 2 and form 3 sets.
Don't think I can make this more vague
Just kidding.
Let's take an example. I make 3 wall textures that tile (not with the other ones but with themselfs). Then I add a door on every texture, this will give me another 3 textures. So I have 6 textures that form 3 sets. One set contains 2 textures: a wall and the same wall with a door.