Russian Presidential aide Ushakov on the EU peace plan: "It is unconstructive, unsuitable."
Russian Presidential aide Ushakov on the Trump 28-point plan: "I would say not all, but many provisions of this plan, they seem quite acceptable to us."

Trump's plan and the EU plan do have differences but on many key issues, the key issues, they are very similar.

What is the one key difference, which makes one plan "unconstructive" and the other "acceptable"?
Who it is coming from. One plan is from EU the other from the US. Russia is prepared to negotiate with the US, and wants nothing to do with the EU.

Putin-Erdogan phone call:
Erdogan is prepared to provide Istanbul as a platform for negotiations.
Putin told Erdogan that the peace proposals were consistent with the understandings reached during the Alaska summit in August, and that the initiative could serve as the basis for a potential peace agreement.

The stage is being set.
Istanbul may serve, once again, as the location for another go at a settlement. The location sits well with Russia as it provides diplomatic continuity in the history of the negotiation process.
Putin confirmed to Erdogan that the Trump porposal (and re-writes that have already taken place and will take place) "could serve as the basis for a potential peace agreement."