Peers reviewing ideas is but one step above rubber-ducking: the peer does not (necessarily) have ideas of its own, but merely serves to verify how you've formulated yours. At least, that's my interpretation.

One is about ideas the other is about values.

"Peer reviewing ideas" is a bad formulation for me.

It's about whether the discussion is general (valid for anyone) or specific (these people, here, now). The latter gives some weight to subjective arguments and arguments from authority, the former does not, and this is a big qualitative difference.