HI !
III. (un supermarché = a supermarket, une épicerie = kind of a grocery store i think ?) Un supermarché is a big store with many aisles/sections. You can find pretty much everything in the biggest ones : food, toys, clothes, media (DVD, video games, etc), books, school supplies, etc ... They're usually in the outskirts of cities.
Une épicerie is smaller than a supermarket. They sell kind of the essentials, mainly food. They're are usually in the city center. Basically, you go there if you need like a ingredient or aliment quickly.
Hope that's clear and hope that helps a little :)
IV. 31. Une boite de conserve (de légumes)
32. Une bouteille (d'eau)
33. Une brique (de lait)
34. Une boite (de pâtes)
35. Un pot (de confiture)
