lewd, crude, vulgar and obscene, whats the difference?

[littlegoku]

I checked several dictionaries and they pretty much have the same meaning.
Can anyone actually point out the differences among these words?

 

[yobarman]

they're called synonyms for a reason..

 

[littlegoku]

They have subtle differences in meaning....

Is like candid and honest..

 

[hjo3]

Ah, screw it.