The difference between isometric and isotonic exercises lies in muscle contraction. Isometric exercises involve muscle contractions without any change in muscle length or joint movement, such as holding a plank. This type of exercise is effective for building static strength and endurance. Conversely, isotonic exercises involve muscle contractions that result in movement, with two types: concentric (shortening) and eccentric (lengthening). Examples include bicep curls and squats. Both forms of exercise offer unique benefits, emphasizing the need for a well-rounded fitness regimen.