Is there much difference between the two?

All charts I've seen have them as basically the same. I use them as such without issue. This comment was from Hodgdon:

""The product name H 4227 has been discontinued. All future lots of IMR 4227 will be manufactured by ADI in Australia. It will look about the same as the old IMR 4227 but will have the advantage of being unaffected by changes in temperature like the Hodgdon line of Extruded Powders.""