When you spend four digit prices on an airgun, you can generally expect:
Craftsmanship in the fit and finish will be much better
Quite often you get a nice piece of wood for the stock, or if synthetic it is still a robust stock, not a flexible flyer.
You can usually count on being able to take it out of the box and shoot it without having to "improve" something like the trigger or the hammer.
It will often, but not always, be regulated.
Guns in this price range are generally very satisfying to shoot.
That said, there are lots of veteran airgunners who buy inexpensive rifles like the Discovery, Urban, Gauntlet, etc because they enjoy the challenge of working on and improving them into rifles that can give the "big guys" a run for their money. I have a Chinese PCP that was one of those humble rifles out of the box, but the guy I bought it from gave it a very elaborate tune. Accuracy, shot count and aesthetic finish were all considerably improved from original, and is a really great shooter.
Whether you consider the finer rifles worth your hard earned dough, or you find you like to buy one of the more inexpensive ones and make it a shooter, is up to you.