The two I have been in are Super U and E.Leclerc. Both function about the same as a Meijer. Then again I don't want to compare anything to Wal-Mart, and all I have ever bought there myself is video games, so that's me. Anyway, they are similar in some respects but very different in others. One of the coolest things is how meat is sold in France. They cut it off, and seal it in this wax paper stuff with this heat bond machine. I was impressed, but then again, it doesn't take all that much to impress me. Both also have in-house fish markets. You can seriously buy anything you like from the sea. We're talking swordfish, scallops, clams, mussels, all that kind of stuff available in a normal grocery store.
Groceries are also much cheaper in France than in the US. I never realized how much more expensive it was until I came to France and saw first hand. French people often buy leeks, turnips, zucchini, etc. right in the grocery store. Fresh bread is also dirt cheap here. The other day at a boulangerie, my partner bought 4 baguettes for under 4 dollars.
Starting with Super U, they are very clean and very well done. I saw one in my partner's hometown that was pretty damn incredible. They just got finished enlarging the store, and now they have to start again. It's pretty incredible looking at how new everything is. The store was very stylish, and has the U-Scans like in the US.
E.Leclerc is cool because they have an additional feature called Scan Achat. Basically, you take a hand held device around the store with you and scan items as you take them. So you run around the store, scanning things, and at the end of your shopping, you go to the register, and they take the information from the hand held scanner, verify it, and then hand you the receipt. Of course, you can only be off by so much, and if you are off by a certain amount a certain number of times, your card's functionality is deactivated, so it's a motivator to keep you honest.
Both stores are really interesting to me, just for the differences in products you can buy. There are a lot more ready made items in France than in America. They have Croque Monsieurs ready made that you just reheat. There's also a huge market for pre-cut bacon, which is not the same thing as in the US. It's definitely an experience, and one you should try at one point in your life.