difference between nope and no

nope - exclamation "Nope" is informal and 'Nope' is very rarely written. You can't say "There's nope milk in the fridge"
(informal) used to say “no”
     ---- “Have you seen my pen?” “Nope.”

difference between no and nope

• "Nope" is very informal; slang. It originated as an extra emphatic "no", with the extra consonant on the end to make sure the listener heard the word correctly. 
  But it's not standard English.
  It replaces 'no' ONLY in the single word answer, "No". You can't say "There's nope milk in the fridge" or "Johnny had nope clean shoes". 

• I think on average, "nope" feel a little friendlier -- a flat "no" can feel a little cold, like the request was annoying or foolish, whereas a "nope" is generally more light-hearted. But it more comes down to tone and delivery -- you can deliver a "no" with kindness or a "nope" that sounds dismissive and sarcastic just as easily.

• "Nope" is informal. You wouldn't usually want to use it, for example, answering questions for a job interview, but it would be an appropriate(нийлэмжтэй, таарамжтай) answer to a friend's question "Have you seen that movie yet?"

• Nope is used informally, normally during chat where you want to give a quick, fluid answer to a question without halting it like 'No' would.
  They both mean the same thing, and 'Nope' is very rarely written.