High-intensity workouts differ from moderate-intensity workouts in approach by focusing on short bursts of maximal effort followed by recovery periods. High-intensity activities elevate heart rates quickly and improve cardiovascular fitness in a shorter timeframe. In contrast, moderate-intensity workouts maintain a steadier effort, allowing for longer duration but less exertion per minute. Both methods contribute to fitness, but high-intensity workouts often yield faster results in terms of endurance and strength in a condensed period, appealing to those with limited time for exercise.