What is the difference between Global Entry and TSA PreCheck?

TSA Pre✓® provides expedited security screening benefits for flights departing from U.S. airports. Global Entry provides the TSA Pre✓ benefits plus expedited US customs screening for international air travelers when entering the United States. Travelers interested in Global Entry must apply through the Trusted Traveler Program website. Global Entry, NEXUS, and SENTRI are programs of U.S. Customs and Border Protection. These programs offer travel benefits to pre-screened members. If you join Global Entry, NEXUS, or SENTRI, use your membership number as a “known traveler number” in airline reservations to receive TSA Pre✓.