System mode means running apex code by ignoring user’s permissions. User mode means running apex code by respecting user’s permissions and sharing of records.
System Mode derives the running code by disregarding the user’s consent. <em style=”font-family: inherit; font-size: inherit;”>For example: If a logged-in user wants to create a record in system mode. Create permission is not required for the creation of records in this mode.
User mode understands the running apex code by concerning the user’s support and sharing of records.