There's no difference in my mind. Both are disrespecting a religion. How do you see it differently?
I don't see making a joke about some one in good fun to be a problem. If we can't laugh at ourselves, then we may as well not laugh at all. For instance, a joke about Christian hypocrisy does not bother me, but an downright attempt to insult someone using that hypocrisy is different to me. There can be funny "dumb blonde" jokes and then there can be jokes about blondes that are intended to insult.
Basically, I think it is the intention that is the key. One person can tell a "bald" joke, I'm bald... or balding, and it can be funny. Another person, can tell the exact same joke, but if he is using the joke negatively it can be insulting.
Immie