As for what the actual engines are... The Kronos and the OASYS "rompler" engine is called HD-1. The scaled down version of the same technology appeared in the M3 and M50 under the name EDS. The technology in the Krome is called EDS-X, which obviously sounds like an enhanced version of what was in the M50; it is not HD-1, so it is not the Kronos engine. The open question is just what differences are represented by the X. Is it basically EDS plus the Kronos derived unlooped piano and drums? Or have there been other enhancements that, while not being full HD-1, may still make it somewhat more Kronos like in its other sounds, compared to the M50? That's the part I'm not sure about.
FWIW, at least for some sounds, I didn't think the M50 and Kronos were all that far apart anyway. I think the biggest sonic benefits of the Kronos over the M50 were to be found in the other 8 engines rather than the rompler engine. But maybe that also depends on which rompler sounds you are working with. Nevertheless, even if the Krome were the full Kronos HD1 engine (which it is not), it would still be missing the other 8 engines (though it has sounds derived in one way or another from two of them), so sonically, apart from piano, I think it would be a stretch to call the Krome a mini-Kronos no matter how you look at it.