In Greek we don't use so many words; there's just one word and that's
it. As in matter of fact, in order to be sure, I placed in google
translate each one of the "unguent/ointment/salve", and even google
always provided with that one single word, which we use in Greece.

So, I can't "feel" the difference each one of these words has when
it's compared to the other.

The word unguent is currently only used in technical contexts in English so far as I know. It's a word a lot of people don't know. Salve feels like something you say of home or primitive remedies, or of something hot that's applied with a pad. Ointment is more common, but it makes me think of stuff you sprinkle on your scalp, and it implies greasiness or oiliness. Cream and paste are certainly the most likely to be used in English, though paste makes me think of toothpaste, which isn't applied topically.

So I wouldn't continue trying to get a feel for the differences between these, because native English speakers aren't likely to have a feel for them either.

-- 
SuStel
http://trimboli.name