Ashen / pallid / sallow / pale (/ livid)

I have these words in my spaced repetition system (Anki). However, when I am trying to guess the translation from my mother tongue, I always guess one of the other three.

Looking for pictures on google I found that they showed very little difference among these. Are they completely synonymous? Can they be used interchangeably?

Livid seems to indicate more bluish or reddish tones, when talking about an angry person. The other three however all seem to be about feeling sick and looking yellowish, whitish.