A SPRAIN......is an injury to a ligament (tough elastic tissue that connects bones) due to overstretching or a tear. One or more ligaments can be injured during a sprain. The severity of the injury will depend on the extent of injury to a single ligament (whether the tear is partial or complete) and the number of ligaments involved.
A STRAIN...... is an injury to either a muscle or a tendon (tough bands of connective tissue that attached muscles to bones). Depending on the severity of the injury, a strain may be a simple overstretch of the muscle or tendon, or it can result in a partial or complete tear.