So, yeah. If you saw that Burger King had added a sausage-egg sandwich on an English muffin and thought that they had ripped it off from McDonald's, you're right. In this commercial, where the King sneaks into McD's HQ and steals the blueprint for the Sausage Egg McMuffin, the chain all but admits that's what it was up to. Says the voice-over:

It's not that original, but it's super affordable. Eggs, sausage, and cheese on a toasted English muffin...

Another difference, as biminitwst points out is that Burger King uses prescrambled eggs whereas at least McD's uses whole eggs in its sandwich.

[via Salon and Raiders757]