There are two possible acceptance criteria: acceptance by empty stack and acceptance by final state. The two are not equivalent for the deterministic pushdown automaton (although they are for the non-deterministic pushdown automaton). The languages accepted by empty stack are those languages that are accepted by final state and are prefix-free: no word in the language is the prefix of another word in the language.
This is the quote from Wikipedia....plz explain why acceptance by empty stack and acceptance by final state are not equivalent in case of DPDA but it is equivalent in case of NPDA