That is 90% the tint and/or CCT of the two lights making a difference, and the other 10% being the high cri led producing more depe reds.
CRI is such a limited way to objectively measure light quality. R9 is just a sliver of deep red taking from a broad spectrum of light— or rather one single color sample. Just because a light has -R9 on its CRI graph doesn’t mean it can’t produce any red content whatsoever.
I bet if you compared a high CRI light with amazing R9, but green tint and high CCT, and compared it to a lower CRI light with pink tint and warm tint but only so-so R9, you’d probably walk away preferring the lower CRI light.
And on the topic of CRI as a whole— it’s a subtle quality to light. It is miniscule compared to CCT and tint. The only real way to accurately qualify how CRI affects light is to pit two light sources of the same CCT and tint against each other, but with varying CRI levels.