difference between

Amedement - retains the original essence remains, but whereas in Modification - the original essence may change.

Amendment Noun:-

1. the act of amending or correcting
2. a statement that is added to or revises or improves a proposal or document (a bill or constitution etc.)

Modification Noun:-

1. the act of making something different (as e.g. the size of a garment)
2. slightly modified copy; not an exact copy
3. the grammatical relation that exists when a word qualifies the meaning of the phrase
4. an event that occurs when something passes from one state or phase to another
   Example: this storm is certainly a change for the worse|the neighborhood had undergone few modifications since his last visit years ago