It's a lot easier to understand the original definitions of townie vs NPC. Townies are those character files in base game or EP (found in files) who can be played if you add them to household. (Including paperboy/girl etc.) NPC has always meant Non Playable Character until people changed it's definition in TS4 to mean any Sim in game, which is totally incorrect. And where all the confusion stems from by the wrong title being applied to a character/Sim.
"Games Are Not The Place To Tell Stories, Games Are Meant To Let People Tell Their Own Stories"...Will Wright.
Comments
I don't think there are any Townies (Mrs. Crumplebottom is one) but there are several NPCs.
https://forums.thesims.com/en_US/discussion/931101/the-sims-2-primer-avoiding-game-and-neighborhood-corruption/p1
Thanks Rflong7.