P-90 pickups / P-94 pickups
The development of the Gibson P-90 pickup started before WWII but really hit the market right after the war when the guitar industry got back on its feet. The P-90 pickups became standard features on every Gibson guitar until they were surpassed by the humbucker pickups. Some twenty years later the P-90 pickup and its huge potentiality was rediscovered.
The P-94 on the other hand, is simply a P-90 pickup that's been squeezed into the size of a humbucker. Sound comparison between the two is an ongoing debate but one detail that really influences the tone is the amount of turns - and it's a challenge to get enough of them on the coil. That's why the coils are made "in house". It's tricky but possible, especially with the 42 awg wire.