How about "compression is DIFFERENT" ?
Particularly as that is a variable measurement, probably not done with a gauge under controlled repeatable conditions, hence, rendering only subjective opinions of the individual. That's not a "bad" thing, it just renders the information less useful to many.

I can tell by flipping the prop through any of my three DL's whether or not they have a "prime" in the cylinder, whether they are cold or hot, and, without looking, probably could tell which was the newer. Because they exhibit different compression "feel" because of all these conditions.

The compression of these seems to change quite a lot based on all these variables.

What I *like* the most, is that they are not "over-compressed", and thus don't detonate on reg. unleaded, and are a little more docile for the timing provided.