The difference between jelly and jam is that jelly is made by filtering out the fruit pulp after the initial heating, whereas jam contains the small pieces of chopped up fruit. However, there are many jokes that play on this question, and most of them are inappropriate. For example, one joke is "Whats the difference between jam and jelly? I cant jelly my dick up your ass". It is important to remember that these jokes are not appropriate for all audiences and should be used with caution.