I don't know if this is because I'm working on my first draft instead of hers, or because the book is tight first person instead of a looser third person, or because of how the line level style choices I make as a solo author differ from the collaborative voice we've developed and been successful at in short fiction. But definitely different.
The biggest issue seems to be word choice. My solo style is wordier and more convoluted than our collaborative style. As noted elsewhere, chemo has not been kind to either my short-term memory or my longer term recall, and one thing I've been struggling with is anomia, especially with respect to proper names.
Normally I have an unreasonably large functional vocabulary and can pick words out of the air like a hunter potting birds on the wing. Now I am struggling to distinguish "mete" from "meet" (as in the adjective meaning "proper"), getting "rood" and "veil" confused, forgetting the various terms for grave-houses, and other such idiocies. I know I know it, I can go look up and sort out what's missing, but it's slowing me down a bit, and frustrating me. Not going to stop me, not for one damned minute, but grr.