I was recently referring to Figma’s help documentation about override preservation, and ran into a part that confused me. Here are excerpts from that help article:
Layer names and hierarchy need to match between the current instance and the variant or instance you’re selecting. This applies both when swapping instances and selecting variants
that first part was very clear to me, but this following bullet is what has me confused:
When selecting variants, Figma will also check if the layer properties you’ve overridden originally match between variants. If so, Figma will preserve your overrides.
I think I’m stumbling over the “properties you’ve overridden originally” … what does that mean? How is it different from the point above about checking for matching layer names and hierarchy? I would love it if there was a supplemental video demo for this point. My best guess at this point is it’s related to “interactive component memory” (not “memory” as in “RAM” or “file memory”, but “memory” as in “remembering”) that @miggi demo’d around this time last year in the Interactive Component Office Hours. I’m not confident in that guess though because my understanding of interactive components “remembering” what interactions happened to it even after navigating to new frames is just a prototyping concept and has nothing to do with overrides one might make in a design file.
If anyone could help explain or demo what that second quote is about I’d greatly appreciate it 
understanding override preservation is really important to me and my team so we can design components that safeguard overrides on common swaps.