Gretsch and Guild pickups are similar in that they are all about clarity and note separation. Whether you are talking humbucker or single coil. Gibsons on the other hand tend to smear the tone more and sustain into a fuzzier, midrangier conglomeration. Both certainly have their supporters and there are a lot more of the latter than the former it seems.
Tom T.V. Jones was Brian Setzer's tech and Brian wanted the Filter'Trons to sound more like the vintage ones. So Tom got to work and came up with the Classic. He has since come out with Power'Trons with more midrange to come to more of a compromise between the two sounds. He also makes Super'Trons that are bar pickups and TV-HTs that are more powerful Hi-Lo Trons. He makes a Magna'Tron that sounds more like a DeArmond but still is a humbucking pickup. It uses magnets for polepieces. He has come up with some new ones including a Brian Setzer model that has a more vintage sound still, a Paul Yandell Duo'Tron (Paul Yandell was Chet Atkins' second guitar player) that is half bar and half pole piece. Finally, there is a new pickup that is supposed to be the closest to the original Ray Butts design.
He also makes versions of the P90, DeArmond, Tele, PAF and Strat pickups that are all unique takes and very highly regarded.
The same pickup can come in several formats including the Filter'Tron style, top mounted DeArmond and full-sized Humbucker style.
I have Classics in my 6120 and Power'Trons in my Starfire V. They are fantastic. This shows the Power'Trons in the Humbucking format: