I used to work at a Ritz Camera. The difference is huge. The main thing is quality control. Do pay the extra for one hour service. The quality is better because the people are actually there and are accountable for their work. Once they know that if they don't do it right, they will do it over, they do get better.
At the first Ritz I worked at, we had a very good team of lab girls. They took pride in their prints, and did not hesitate to reprint due to bad color or dust. One girl printed, another girl did quality checks.
People used to ask how much a roll cost to develop, and we would say: "$7.99 for double prints on 24 exposure rolls" Their jaw would drop and they would quote Wal*Mart's $3 price, single prints, 3 1/2 x 5 vs. our 4x6. X-( We would unapologetically say: "We'll match our
quality against anyone's." and "You get what you pay for."
Some people would leave and go to Wal*Mart. Good riddance, cheapskate. Others would give us a try and pay the money one time, just to find out. People could AlWAYS tell the difference. There were no technical flaws and the color & exposure were corrected better.
Even my mom, who can barely operate a point & shoot, and can't remember how to cancel or force flash noticed the difference when I was dating the lab girls. They raised her standards, and all of a sudden, even the deluxe Walgreens wasn't good enough, hehehe.
As for sye-sub digital, there isn't a real difference, except the paper and how well the machines are maintained.
A couple weeks ago, I had some prints made at my local pharmacy. They are walking distance from my house, so I consider it worth the time to get them trained.

4 of the prints had light scratches on them because something in the machine was dirty. I found the lab girl and said I would like her to clean the machine so I could reprint the 4 that had the scratch or whatever right on the person's face. She cleaned it, and the prints came out very nicely.
The way I see it, if I get prints that are technically good, I will take them. If they're bad because of ME, OK. If their people or their machine screwed them up, that is unacceptable. I am a photographer, and this is my product. I won't settle because some kid is too lazy to do it right. I'll MAKE him or her do it right. Worst-case, I talk to the manager, and if that doesn't work, I leave and never go back. Vote with your wallet, my friend.
One time, when I was having prints made in Krakow, Poland for my vacation, I dropped the film off at a one-hour lab. Their prices were high, about $9 a roll. I asked my wife to warn them that I am picky and that I won't take sub-par prints. I think she was a bit embarassed, as they apparently aren't such demanding customers there. That, or she was too diplomatic.
A couple hours later, I came back for the prints and about 3 per roll had dust on the negative. Only one print out of 6 rolls was mis-printed. The guy was upset. He went over the prints with a loupe, to make sure they were dust and not a reflection. (A couple of them were reflections) But they reprinted the ones that weren't done right. My wife was embarassed, the staff were a bit angry because I slowed them down, and all the other customers were staring at this American with his Polish wife who was making trouble. Tough luck for them. At my workplace, if we miss something or do it badly, we do it over, so it doesen't save time to do sloppy work.
Sorry for the rant.
If you want to save money, have them printed at a Pharmacy or Wal*Mart, but be ready to make them reprint. (maybe for snapshot-type stuff, this is a good option)
If you want quality stuff, go to a photo specialist. It isn't THAT much more, and they usually have a Frequent Photo club or something with good benefits, if you keep going back. At Ritz, we used to give free Agfa film or free double prints to members. We even did the math as to how many rolls they would have to have developed for the membership to pay for itself.