EU isn't a military organization, so trying to compare Russia with EU, doesn't make much sense. If the EU will officially have its own army, then you can compare them. At the moment you may compare Nato with Russia as they are both military entities.

The south-eastern flanc of NATO especially, doesn't look good at all. Turkey is the main force and is more friendly to Russia than to its allies that it sometimes threatens (take Greece). So you can't really rely on them for offering support in case of a russian attack. They may stay out or even join Russia. Greece has big economical problems and Tsipras, who is a Putin admirer and made controversial statements about Russia's actions in Ukraine, doesn't inspire much trust either. He might really take his time to think whether to send troops if a russian attack would happen on the eastern flanc or not. Especially if he is offered a good deal to stay out. Romania and Bulgaria have small armies, mainly use old outdated military equipments, some areas of their military are completely neglected because of a lack of investments and would have a really hard time defending themselves against a big concentrated attack on their part of the flanc. You have to be able to keep the front on your own for at least 2-3 days till help can be sent from further away. So those in the west shouldn't relax too much that there is a lot of distance between them and Russia.

The one thing that is obvious is that Russia doesn't have the money to finance a long regular war, for now. But if oil and gas precisey will go up so he can make some decent reserves, that may change. Still, they can't support a long war effort alone (having many factories ready to built war equipment, for example), so they could only try a blitzkrieg in Eastern Europe to put more distance between Moscow and the Nato flanc and hope he'll end up negociating on Eastern Europe with the west, giving a few territories back without a single fire being shot but keeping most of it, especially the best strategic positions.