H4895 and IMR4895 are now identical per Dave at Hodgdon.
Before Hodgdon bought out IMR, IMR 4895 was a DuPont product, made in Canada. Since Hodgdon bought out IMR, you will notice Hodgdon has discontinued H4895 and now sells only IMR4895.
What is currently sold as IMR4895 is actually made by ADI in Australia, imported by St Marks in Florida, same as H4895 has always been.
Hodgdon marketing gurus decided the brand name IMR4895 was more in demand, and some have always considered H4895 a knockoff so the marketing name H4895 was eliminated from the marketing lineup, repackaged in (purple label) IMR4895 packaging and the rest is history.
Before anyone jumps in and disputes this, keep in mind DuPont (Canadian) manufactured IMR4895 is NOT the same as ADI manufactured (Australian) H4895. IMR4895 manufactured in Australia (by ADI) is. Call Hodgdon, ask for the lab and verify for yourself.
Check the origin of your powder by checking the label on the container, and as always work up ANY load instead of blindly using data from any unverified source.