Method and device for performing communication between terminals in wireless communication system

A sidelink transmission terminal in a wireless communication system, the sidelink transmission terminal comprising:

• a transceiver;
• and
• at least one processor configured to:
• determine a type of a core network (CN),
• determine whether to activate a service data adaptation protocol (SDAP) layer function based on the type of the CN,
• based on a result of the determination, transmit a message indicating whether to activate a SDAP layer function to a sidelink reception terminal,
• determine to establish or release a service data adaptation protocol (SDAP) entity related to sidelink communication, based on SDAP configuration information, wherein the SDAP configuration information includes a cast type associated with a destination identifier, and the destination identifier relates to a destination of the sidelink communication, and
• establish or release the SDAP entity, based on the determination to establish or release the SDAP entity,
• wherein the cast type associated with the destination identifier is one of unicast, groupcast, or broadcast.