The difference between the two songs is the one about Gypsies is about "us vs them." (Beanster pointed that out quite well.) There's only one name of a Gypsy in the entire song, and most of it refers to just "the Gypsies." Mrs Stein doesn't rent to Gypsies. Not certain Gypsies, but ANY Gypsies. The song says, in effect, that they're all the same, and they're all bad. The one about Pat Murphy has a lot of names in it, and never once refers to an entire group of people. You could change the names to people you know, and it probably would work, although there is a bit stereotype implied, and all the names sound Irish. The Pat Murphy song at least sounds Irish, and there's a big difference between poking fun at your own and attacking people who are different.