What is the difference between irony and sarcasm ?

An irony is a statement that, when taken in context, may actually mean something different from, or the opposite of, what is written literally; the use of words expressing something other than their literal intention, often in a humorous context.

While

Sarcasm is the use of acerbic language to mock or convey contempt, often using irony and (in speech) often marked by overemphasis and a sneering or snarky tone of voice.

Sarcasm is the lowest form of wit.

dramatic irony occurs when the reader/audience knows more about a character's situation than the character does. the one main effect is that it gives the reader a sense of superiority, or detached superiority. the reader not only seemingly discovers what is revealed, but feels superior for doing so.

i will try let me see what they are first