Lists are pretty similar.
Revolvers. Same list, except <50 goes with a Taurus 856, >50 with Ruger Sp101.
Rifles, Same list, but <50, a Diamondback something, >50 Bushmaster.
For revolvers and rifles, over 50 goes with stuff that's a tiny bit bit more expensive.
Autos, a few more differences, that I'm not sure how to interpret.
Is age 50 a good dividing line for this?
Semi Auto's:
The Hellcat is the newest thing out. Appeal of single stack small handgun for newbs, the one thing collectors wouldn't have. Not surprising for both lists. Same goes with the Sig micro, newer single stack.
G19, M&P, P320, Sig p320, and Beretta 92 are all the newb guns. Lot's of new gun owners in the over 50 crowd from the rush.
Younger for Glocks in general. Cheaper, collected more by younger crowd in variants.
Same with XDs, thus the XD(M)
Old people still think Kimber is a thing.
KelTec and Ruger pushed for arthritic hands.
And no, I don't think 50 is a really good line for that. I'd bet you'd actually see trends if you cut it up more.