both will return last inserted value in table but scope_identity is limited to current scope and current session and current_identity is limited to current scope but not limited to current session

http://www.mindfiresolutions.com/Difference-between-IDENTITY-SCOPEIDENTITY-and-IDENTCURRENT-in-SQL-SERVER--1177.php

Scope_identity and current _identity both are similar and it will return the last identity value generated in the table. Scope_Identity will return the identity value in table that is currently in scope