So now two 11-24s ?
Wonder if both these rumours could be connected, would it be EF-S or EF though?
Apples and oranges -- a coincidence of numbers, nothing more. If both rumors are true, the EF 11-24 will look like a completely different lens than an EF-S or EF-M 11-24, and their optical design would be quite different.
Designs can vary a bit, but I'm guessing an EF-S/EF-M 11-24 would resemble one of the three crop ultrawides they sell today (EF-S 10-18, EF-S 10-22, EF-M 11-22), but an 11-24 full frame EF lens would look like some altogether new hybrid of a fish and an ultrawide zoom. Unless they'd want a flat leading element the size of a teacup saucer, you'd expect the leading element of the EF lens to be exceptionally bulbous and almost certainly lack the ability to be front-filtered.
I think you can loosely compare the 10-22s of the crop world to the 16-35s & 17-40 of the FF world. But once you get down under 16mm, FF lenses get bulbous very quickly and the similarities fall away.