Idiomatic problem

Many a times I have noticed these wordings in English text....

"In Contrast With"
"As opposed to"
"Unlike that of"

(// Please do correct If these Idioms's are not correct)

Are not all these making some contrast ?? My problem is I confuse what to use when because it seems to me all are just doing the same thing ...i.e contrast.

Do you have a diagnostics check what to use & when ? or some kind of tips to remember these idiomatic use ?