The G19 has a very long excellent history.
All About the G45:

Glock 45: All About the G45 - The Mag Life

What is a Glock 45? How is the G45 different from the G19X? Wait, do you mean the model or the caliber…and which caliber? Let's clear it up.

gunmagwarehouse.com

There is a lot of info on the net about both.

 

Google difference in glock 45 and glock 19
Also handgun hero .com for side by side comparison.

 

Also the baseplate. The G45 uses the gen 5 baseplate, which is larger than the gen 1-4 baseplates. So if you already have gen 3 or gen 4 G17s or G19Xs, the G45's magazines will not fit them. You can easily swap out the G45 baseplates and replace with gen 3-4 baseplates.

 

Hmm. Did not know this. Good info thanks.

 

I own both. The difference to me? The G45 is a little bit better range gun to me as I have fairly large hands. I’d conceal carry the G19 while I’d only open carry the G45 due to its longer grip. That said, I generally don’t open carry in public.

 

The few people (maybe 3) I’ve seen at the range with a G45 all rave about it’s accuracy and shootability. And all had owned/shot other Glocks previously. None could put their finger on why they like and shoot it better.

 

G45 7-round group from 25 yards, leaning my shoulder against a post to steady.

G45 10-round group from 25 yards, 1-handed, unsupported.

 

Nope. The G17 size grip is pretty much it. IMO I think it makes the G45 just ever so slightly more controllable with muzzle flip with that extra grip than a 19.

Also the baseplate. The G45 uses the gen 5 baseplate, which is larger than the gen 1-4 baseplates. So if you already have gen 3 or gen 4 G17s or G19Xs, the G45's magazines will not fit them. You can easily swap out the G45 baseplates and replace with gen 3-4 baseplates.

You can use Gen 3/4 or Gen 5 magazines in any of G17's or the G45. Gen 5 magazines are only a problem with the 19X.

 

I carry a G45 just as easily as a 19. Cannot go wrong with either. Shooting the G45 suppressed is much better feeling than on a 19. Feels much more balanced having the fuller grip

 

I own a G45 and also shot a Gen 5 G19. I prefer the G45 due to the longer grip. The G19 has a cut out on the bottom of the front grip that is used to pull a mag out, and that just bothers my grip on the gun.

 

No, that is exactly the difference. the G45 is a G19 with a longer grip. Get the 45 for competition, but get the 19 if you are buying it for concealed carry.

 

I’ve got both, and they are both great.

For some reason, I shoot the 45 much more accurately than the 19. The feel and balance are just better on the 45, but you can’t go wrong with either.

 

I was debating on getting the 45 or 19 at the store. Honestly, either one would be fine. I chose the 19 because it gives me the added versatility and I already have lots of extra 15 round mags which I didn't want to go to waste. But if I picked a 45, I would still be happy.

 

hand gun hero is a great site. just when you thought everything was already invented...