Fender: Eearly 50s we can think of Broadcaster or Telecaster. Late 50s means Strat with maple finger board, and sometimes soft V neck. 60s usually means rosewood fingerboard, and late 60s means big headstock into the CBS era. Many players loved the 50s strat e.g. Clapton. 70s Fender with big headstock, 3 bolt neck are usually not so desirable but very subjective, e.g. Jimi and Malmsteen love 70s strat.
Gibson: 50s Les Paul neck is chunkier, 60s have slimmer neck. SG also was launched in the early 60s, but Les Paul wanted his name removed from the product. Due to Clapton, Gibson resumed the production of Les Paul from 67'