The short answer is that Clear allows members to verify their identity using biometric scanning ahead of airport security, whereas Global Entry expedites re-entry into the U.S. after international travel. Clear allows you to hurry through security lines faster at 50-plus airports around the United States.
I am having trouble with my Global Entry/NEXUS/SENTRI membership; whom can I contact? If you have questions or concerns about your Global Entry, NEXUS, or SENTRI membership, you may visit the Trusted Traveler Program website or contact Customs and Border Protection at (877) 227-5511 or by email.