A sprain is a stretched or torn ligament. Ligaments are tissues that connect bones at a joint. Falling, twisting, or getting hit can all cause a sprain. Ankle and wrist sprains are common. Symptoms include pain, swelling, bruising, and being unable to move your joint. You might feel a pop or tear when the injury happens.
A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can cause a strain. Strains can happen suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing sports. Symptoms include pain, muscle spasms, swelling, and trouble moving the muscle.
At first, treatment of both sprains and strains usually involves resting the injured area, icing it, wearing a bandage or device that compresses the area, and medicines. Later treatment might include exercise and physical therapy.
NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases