what exactly makes a belt a "gun belt" ? Also, where can I get a QUALITY holster?
The guys have pretty much covered what a gun belt is. If it makes a difference I wear a Wilderness Instructor's gun belt. It's pretty much the standard if you're looking for a non-leather gun belt. I love it.
As for holsters... asking where you can get a quality holster is like asking where you can get a quality car...
... ie: it's not that simple... and everyone's got their own opinions.
Regardless of the brand of holster... you want to make sure the holsters you end up with have the following elements:
1. The holster, whether kydex or leather, must be molded specifically for your gun. This will aid in retention of the firearm. You can run, jump, hang upside down... and the gun is staying in the holster. This is not the case with ballistic nylon "universal" holsters (Uncle Mike's, etc). The last thing you want is for the gun to fall out when you bend over, lie down, etc doing every-day things.
2. If the holster is made of leather, you want the holster to have a reinforced mouth. This keeps the mouth open for one handed re-holstering. If a holster does not have a reinforced mouth, especially with IWB holsters, the mouth will close right up and will be a pain. You do not want to have to fumble around with your holster trying to get your firearm back in.
Everything else is a matter of preference. ie: the cant, how the holster attaches to your belt (standard clips, c-clips, j-clips, closed loops, snap loops, etc), leather vs. kydex, brand, etc.
I prefer kydex to leather for a couple of reasons. Kydex doesn't hold moisture. Kydex is easily cleaned. Kydex can be thinner than leather, giving you a thinner overall profile which leads to better concealment. Kydex can also take more of a beating.
However, there's nothing wrong with leather holsters. Some prefer leather because they feel like it is more comfortable against the skin compared to Kydex. And if you want a holster that looks great too... then you want a leather holster.
Just know that both can and will wear the finish on your gun.
A couple of great Kydex brands are Raven Concealment Systems (RCS) and Comp-tac. RCS has one of, if not the most, concealable OWB holsters out there. I use the Phantom holster and can conceal my G26 or G19 OWB with just a tshirt. Comp-tac makes excellent IWB holsters... I use the CTAC Slide.
There are a TON of good quality leather holsters out there... I'm sure others will have good suggestions. Milt Sparks, Alessi, O'Rourke, Mitch Rosen, Kramer, R Grizzle, TT Gunleather, and on and on.
You will have to try them out and see what works for you. I know that "trying them out" can be expensive... but there's not much you can do about it. Or, if you know someone that has a holster you're thinking of getting... ask to meet up and try it out. I'd be glad to let you try anything I have and I'm sure others here would be too.