This has bothered me for a long time, the use of “unavoidable” when to me “inevitable” sounds much better.
Looking it up on dictionary.com:
The fact that the former cites the latter as a definition makes me :dubious:. And yet, I can’t see much difference beyond this: Inevitable for some reason sounds like a more long-term idea, more like destiny or fate than what’s going to happen tomorrow.
Are they the same word? Or is there a substantial difference I am missing?
The death of the sun is inevitable.
The deer in the road was unavoidable.
In my area, the deer in the road is inevitable as well. 
I agree with Harmonious Discord: the fine distinction between the two is that inevitability is an inherent quality, not the result of choices which have been made. Something becomes unavoidable, something does not become inevitable.
Thank you, that is a great explanation, and it only reinforces my superstition that people around me have been using them interchangeably when they are not in fact so. I’ll be sure to point this out, it’s bound to make me really popular! 
I always figured that inevitability implies a time element; it’s an event that will happen in the future. Unavoidability could be used to describe something that occurs for a variety of reasons. I believe Harmonius Discord was making the same point; if you hit a deer in the road it might have been unavoidable but it was not inevitable.
Well, would you consider it inevitable or unavoidable that you would make a decision that would bring such popularity to you?
Unavoidable that I would make the decision, inevitable the result that follows.
Sometimes either can be used. My eventual death is both inevitable and unavoidable, and both mean pretty much the same thing.
Well, yes, I agree, but
Look Out! TRUUUCCCKKKK!!!
Ah, hell.