Say there is a non-NATO, non-EU country, yet not Ukraine, at least not yet. (I stipulate the last because I don't want the current crisis to yet color the answers.)

What are the actual requirements as listed in the treaties or charters for defense and/or aide to be provided by other member nations, if:

The country is granted EU, but not NATO membership?

The country is granted NATO, but not EU membership?

Do things drastically, or at all, change if both are granted?