As verbs the difference between append and postscript
is that
append is to hang or attach to, as by a string, so that the thing is suspended; as, a seal appended to a record; the inscription was appended to the column while
postscript is to extend (a letter or another document) with additional remarks.
As nouns the difference between append and postscript
is that
append is (computing) an instance of writing more data to the end of an existing file while
postscript is (countable) an addendum to a letter, added after the author’s signature.