Flex Seal is liquid rubber in a can. It sprays out as a thick liquid, seeps into cracks and holes, and dries to a watertight, flexible, rubberized coating that stops leaks fast.
Flex Shot is a super thick rubber sealant that caulks, bonds, and seals, without the need for a caulk gun. It has a silicone-based formula and creates a watertight, flexible barrier.
Which product you use will depend on your specific repair or project.