Please bear with the stupid questions, but I think the penny has dropped:
Kit brewing, you buy a can full of malt extract, and I've heard references to Isomerised Hop Resins. Now I don't know WTF these are but it sounds chemistry lab rather than brewery. Isomerised hop extracts are hops that are processed in a factory and do not require boiling Also, with the ten quid type kits you add sugar - this is basically unnatural? Not necessarily unnatural but not best practice.
Extract brewing, you might use cans or packets of malt extract but add other grains (eg crystal malt) and real hops, and certainly no sugar? That's pretty much correct :thumb:
All Grain - doesn't sound much more involved than Extract, or am I missing something? The only difference is that you make your own fresh malt extract during the mash :party: You also require a mash tun.