Yes, there is a difference. Like kit say, consistency is one. Neighbourhood labs may not be consistently good. So if the shots are important to you, then send them off to a good lab. Remember that you've already spent a lot of money in your equipment, and a lot of time and effort and creating your masterpieces, so why stinge on the final output?
Of coz, if they are just casual snaps of friends, etc and your main objective is just to give them a copy of the print and they couldn't care less, then the lab doesn't matter.
i usually send my 4R prints to the lab.
and like what the others said, consistency is the key-word.
my sis tried to send to neighbourhood labs, and for the same set of photos, there can be some which are quite greenish, some ok-ok..
so from then on, she send to e-color at balastier point for printing. and she's usually charged $0.30 per piece for big quantity. Which is very cheap!
for me, i send my batches of prints to the shop around my place - i wont say they're fantastic or the exact opposite - but then again, i have never tried a prolab, and so i can't impose such a judgement. but i must admit that it's a pleasure to pop by the store where the staff will yak and chat with me. main concern for me is the cost-effectiveness and a bit of convenience. i'm not a prophotog, so i can't be toooo bothered to running off to town to send in prints, and collect them on another day from town - i'd be running myself into the ground if i did that!
if a person asked me if i print my own photos or via a lab, i'll say i dont print my shots myself - partly i dont fancy buying a high end printer, and topping off the expenditure lists (aka ink) and high grade paper, and more importantly, "experimental wasted" prints + ink. and not forgetting i haven't ever calibrated my AOC monitor, which would likely be a waste of $$$ and time. the economies of scale works very well for the shop, why should i bother myself with the consumables, when i can selectively print from the almost 30K shots on my hard disk?