Welcome to the forum.
There's really no reason to confuse yourself. Any and all diets ride on the foundation of this:
You must be in a caloric deficit.
Every diet out there finds some way to get you in an energy deficient state. It might be through exercise, caloric restriction, macro-nutrient restriction, worship to the Gods, a combo of each.... WHATEVER!
For most around here, it seems simply monitoring calories works best. Have you read the stickie posts yet? If not, I highly suggest reading the stickie titled: Words of Wisdom. There's a lot in there wrt setting up diets.