Lifting weights isn't all the same thing. There are plenty of different things you can do to change the way your training affects your body and performance.
Strength
Strength training is a form of training that is used to improve the body's ability to move a load. This is typically done with compound (multi-joint) movements like squats, presses, and deadlifts. Not only are muscle fibers training during strength workouts, but the central nervous system gets worked hard too. General repetition schemes for strength range from 1-5 repetitions per set.
Power
Power training is a form of training to improve the body's ability to move large amounts of weight in short periods of time. This type of training is often used with athletes to improve explosiveness. Compound movements like squats, presses, and deadlifts are also common when training for power. General repetition schemes for power training range from 1-6 repetitions.
Hypertrophy
Hypertrophy training is a form of training to increase muscle size. When it comes to muscles, the word "hypertrophy" refers to an increase of that muscle's cell size. General repetition schemes for hypertrophy range from 8-12 repetitions.
Although strength, power, and hypertrophy generally have their own rep ranges, it's beneficial to incorporate many different repetition rep ranges into your routine regardless of your goals.