Qual è la differenza tra replace A with B e replace A by B ?Sentiti libero di rispondere con un esempio.

"To replace" can be used like "I replace x with y" or "X replaces Y". But you can't say "I replace x by y."
Sentence 1 and 3 are fine.

Anger replaced fear. "X replaces Y"
Fear was replaced with anger. - Passive form of "I replace x with y"
Fear was replaced by anger. - Passive form of "X replaces Y"
I replaced anger with fear. "I replace x with y"

There is a problem with sentence 4.
Margarine replaced butter.
Butter was replaced by margarine.
Butter was replaced with margarine.
I replaced butter with margarine.

These are your options. You cannot say "I replaced butter by margarine."