French hypermarkets are somewhat regional, so depending on where you're going you might see three outlets of one chain, and none of a couple of others that you've heard of. Ditto for supermarkets (the difference is mostly the size of the building and whether or not they sell fridges). There certainly isn't any kind of national ranking by perceived status. (Many European people who visit the UK are surprised by the relative importance of brands in general.)
Hypermarkets tend to be surrounded by other shops in an indoor single-storey mall, like bakers, snack bars, florists, shoe shops, key cutters, etc. There may be a cheap chain restaurant or "cafet'", and possibly a McDonald's in the car park.
In general they are less focused on service than UK supermarkets. If you ask someone where the eggs are, they won't have been trained to walk over there with you. You may also find that they don't seem quite as clean, the floor tiles are cracked, etc. There might well be someone at the entrance asking for money.
You may be surprised at how much processed food is on sale. There will be a huge selection of frozen pizzas. About 15 years ago France also discovered wine boxes, which are called (literally, using the English words, "Le Bag In Box") - but the wine in them is generally quite good.
(Excuse any slight lack of enthusiasm, but I lived in France for a couple of decades, and a weekly shop for a family with kids is pretty much the same amount of fun everywhere!)