Here are some key differences:
1. TSA PreCheck expedites the security process by putting you in a shorter line to get your documents checked and allowing you to keep your shoes, laptops, liquids, belts, and jackets on you. Meanwhile, CLEAR expedites the security process by letting you bypass document verification altogether with the biometric screening. If you have TSA PreCheck, you'll move on to the physical screening and still enjoy the benefits of PreCheck. If not, you will be physically screened per the standard rules.
2. TSA PreCheck members can get randomly excluded and sent to the regular line. CLEAR does not have random exclusions.
3. TSA PreCheck only works with certain airlines, though it's available in many more airports nationwide. CLEAR works with any airline, but its rollout in airports is still limited. CLEAR is also available at some sports stadiums.
4. To enroll in TSA PreCheck, you submit an online application and schedule an in-person appointment at an enrollment center. The appointment includes a background check and fingerprinting. To enroll in CLEAR, you submit an online application and visit an airport location where you undergo a background check and fingerprinting. No appointment is necessary.