No.
PS is for when you’re in the middle of writing your piece but want to add something without changing your original piece but haven’t posted it yet.
EDIT is for when you’ve already publicly posted your piece but want to go back & change it.
PS is for a self-contained end note. It's kind of like a semicolon.
EDIT is used to explain why the system stamped "edited" on a post. Sometimes that edit is more of a postscript, but it gets tacked on under "EDIT" instead because the post is going to say it was edited, so better to let it explain itself.