Ilford Fixer: Rapid vrs Hypam

Any difference between these two fixers for B&W, except that Radid is non compatible with hardeners, and Hypam is?

They tend to be available in different package sizes. And I don't know that the Hypam was commonly stocked by a lot of the stores that served the hobbyist market.
I'm sure there are other practical differences in a commercial environment, but I've not encountered them in a hobbyist's darkroom.

For many years Hypan was the standard name for all sizes of Ilford fixers, then a few years ago Ilford decided for reasons only known to themselves, decided that the 500ml and 1 litre sizes would be in future called Rapid fixer and the 5 litre pack would be the only one called hypan, but for all practical purposes they are oe and the same product, just a different name for different sizes

They are slightly different formula, Hypam has additional buffering allowing it to be used with a hardener that Ilford also sell (or used to). The buffering is needed to maintain a constant pH at as the hardener fails to work effectively if the fixer acidity drops and it's on;y pH 5.4 to start with.

Ilford Rapid Fixer lacks the additional buffering so can't be used with a hardener, aside from that they are essentially very similar in use.

Ian