I've looked this up several times but I haven't found an explanation succinct and clear enough so that I could actually keep it in my mind.
It would be great if somebody could describe a simple mental model that is easy to remember.
For other classes this might be something like:
Druid: Nature based magic, often shapeshifter
Cleric: God based magic, mostly healing
Now, clearly these are oversimplifications but at least in this way the concepts mean something to me. Warlock, wizard and sorcerer (or mage, witch - but those aren't used in Dnd, right?) on the other hand are just in the same bucket in my head.
So please help me split them up. :)