H110 and W296 are made in the same plant and are, in fact, the same powder. The difference is whose container it ends up in. The difference you see in load data are due to noraml lot-to-lot vaariance, the differences in the individual firearms used to collect the test data, etc.
There are other powders with similar names that are NOT the same. IMR4198 and H4198, IMR4350 and H4350, etc. But, for now, H110 and W296 are the same.