S5 text message settings.restoring. What will happen if I restore them?

[AC Question]

S5 text message settings..restoring.

on my s5..in the text message settings..i have the option to restore deleted messages from my sim card. if i do this..will it delete the othee saved messages i have? will it show every message ive ever gotten? And will there be a way to tell which messages are my saved ones and which are the ones i restored? thanks