Oh there is your problem right there.. The salts are salts statement applies to different sources of the same salts.. I guess I thought that much was obvious.. As far as the NPK sources themselves go, salts are salts, cations are cations, anions are anions.. Its management of them that is key.. And thats easier said than done with some cheaper mixes, and even moreso if you use multiple products..
Fancy fertilizers are more than salts alone these days, but its worth noting that alot of the extras are only redundant sources for things that should already be in healthy soil..