Both “refuse” and “reject” can mean not to accept something, but their uses can be very different. Refuse can take a direct object or it can be used with an infinitive verb. Reject cannot be used with other verbs. It only takes a direct object.

As verbs the difference between reject and refuse is that reject is to refuse to accept while refuse is to decline (a request or demand). As nouns the difference between reject and refuse is that reject is something that is rejected while refuse is collectively, items or material that have been discarded; rubbish, garbage or refuse can be (obsolete) refusal. As a adjective refuse is discarded, rejected.