I see what you mean. It actually sounds like they overcomplicated the system and randomly applied different names for some things, but not others.
So you have character level, which increases with experience.
Weapon, Armor and Class skills, also have levels, which increase with experience. And the individual abilities also have levels that are different from the skill tree levels (which are different from the character level) and they note that having skills slotted gives you extra experience in those abilities, and it doesn't matter if you actually use them or not, just that they're slotted. Which means farming trash mobs until you get your abilities up to morph level, at least. Fun.
And crafting abiltiies also have levels, but those are gained through experience points called inspiration, and guild abilities gain experience points called reputation.
And you also have ranks, which they also use as a synonym for level elsewhere in the article, but they actually mean pvp ranks, which also give you skill points like levels do.
Finally skills, abilities, Feats and Spells are used almost interchangeably, except feats and spells use different pools. And passives can eat multiple skill points to power up, but presumably increase by whatever tree they are on since they can't be slotted. (And so can't have their own levels, either, unlike active abilities. Presumably).
But I guess all you get for crafting is the ability to craft more. Unless they don't know or are leaving bits out, which may or may not comfort you.
But at least the system overall is clear, yeah?