Tendons and ligaments are commonly confused in their identity. However their anatomical functionality is vastly different.
Tendons consist of connective fibrous tissue that connects muscle to bone. The major function of tendons is to enable movement of the body parts by acting as intermediaries between bone and muscle. For e.g. Achilles tendon connects the calf muscles to the heel bone. Tendons are vulnerable to tearing and tendonitis so due care has to be taken to maintain flexibility.
Ligaments, on the other hand, are similar to tendons in their structure but connect bone to bone. They are composed of tough, elastic collagenous fibrous tissues providing stability to the joints. Overstretching the ligaments could compromise on the stability of the joint. An example is anterior cruciate ligament found in the knee joint.