In my testing of H4895 in 308, if there is a real difference over the chronograph between the two, I did not see it.
There is not a big difference visually, other than H4895 is green.
Hogdon told me that H4895 was one of their extreme powders, so the chemistry is different. But I don't know if the pressure curve is all that different.
If you are loading maximum loads, then any change, lot to lot, case, primer, primer lot, will make a difference. But if you are loading mid range loads?, I doubt a change from H4895 from IMR4895 is going to make any difference.
I know loading manuals show different pressures, but then, you saw the same differences for H110/W296 and HP39/W231. But now we know these were the same powders. So the differences you see in loading manuals between similiar, if not identical powders, may be just the difference between lots.