I feel like there is a difference, but sometimes it is worth it too me, and sometimes not.
The most dramatic difference that I could show you would be if you go on most snap on trucks, they will usually have a little board there with some rounded bolts and a variety of sockets from different brands, the snap on will hold and the others will not.
At one point I was an aviation sheet metal guy, and the guy that had to pull out the rounded and stuck bolts etc. I cannot tell you how many times I would go to the aircraft that the mechanics could not get the screws with 5/16" heads out of and I would go there with my Snap on stuff and pull it right out. That display board they have is not a "trick". That said, my 1/4" stuff was snap on, my 3/8 stuff was Mac etc. My 1/2" stuff was Craftsman / Penncraft and my 3/4" stuff was chinese. My wrench set was an S&K that I really like the feel of but the smaller 5 or 6 wrenches (below 9/16) are Snap on's that I probably paid as much for each wrench as I did for the S&K set.
I think there is a place for all the tools, we were talking about the chinese wrenches last night, in general, their quality is junk, but, about two weeks ago, I was in Louisville with the mowing truck and tractor, and broke a loader mount, pulled out the cheap chinese wrench set, put it on the bolt, pulled out the $2 claw hammer and beat on that wrench and got the bolts out, would never have done it with my "good" tools that way but fixing that one job was worth what I paid for those tools right then.
Anyway, are they better, yes, but as Bird pointed out, there are multiple reasons that professional mechanics choose them, not the least of which is the payment plan. Are they the better value for everyone, absolutely not....
I still get sick every now and then when I am out on the tractor working with the wife, and I will look down and she has my $60 snap on ratcheting extended screw driver digging mortar out of the concrete mixer (a personal favorite of mine, a tool that just put's a smile on my face everytime I use it) We are then off to Bill's Wholesale for an assortment of cheap and junky tools just for her!