In many articles, as well as in common usage, you will often hear or see "weightlifting" and "strength training" used as if they are the same thing. Technically, however, they are not.
Weightlifting is a type of strength training, of course, but it is not the only one, and weight training can be used to accomplish other purposes, such as weight loss, or sport-specific training. The whole goal of strength training is to build muscle mass and thus increase strength.
You build muscle mass by forcing muscles to work prgressively harder against an opposing force. In weightlifting, that force is most commonly gravity. You use your muscles to lift either a free weight or weights mounted on some sort of exercise apparatus, such as an all-in-one exercise machine against gravity. But, there are several other methods and strength training exercise too - such as resistance strength training, in which you use the muscle to overcome resistance like that of resistance bands, or resistance machine that uses a series of pulleys
You could also use isometric exercises for strength training. That pits one muscle against another or against an immoveable object.
Even with the many options available, most fitness professionals agree that probably the best method of building muscle is to strength train through weightlifting. And for the purposes of this discussion about how we build muscle and the many benefits of doing so, the terms "strength training" and "weight lifting" will be considered interchangeable.
In fact, prior to these modern times where we have learned so much more about physiology and exercise, and other methods of strength training exercises have been developed, than in the days of Eugen Sandow, or even Charles Atlas, strength training and weight training were pretty much interchangeable terminologies and technologies.
Regardless of whether you wish to call it strength training or weightlifting, this sort of exercise can provide significant health benefits in addition to improving strength.
Strength training, while building muscle, also strengthens bones and ligaments, aids in weight loss and weight management, and adds to the weightlifter's overall fitness and well-being. The method of using weightlifting to increase strength is to use the concepts of progressive resistance and overload. You need to tax your muscles by increasing, from workout to workout, over time, the force (resistance) they need to work against to continue to make the body increase muscle size and mass in order to gain strength.
In basic weightlifting, you do this either by adding more weight, increasing repetitions, or by increasing "sets" of repetitions.
Weightlifting, whether done with either free weights or all-in-one machines, is also a great way to strength train because weight lifting exercises work targeted and specific muscle groups. This means you can opt to do extra, or more focused work on areas that need more training.
For example, if you need to add strength to your legs because you are a soccer player, you can target leg-lifting exercises, such as the squat, and still receive many secondary benefits of weightlifting and general strength training at the same time.
While they use pretty much the same equipment and exercises, weightlifting is not the same thing as bodybuilding or fitness training.
Popularized by the Movie "Pumping Iron" and rise in fame of Arnold Schwarzenegger, bodybuilding uses similar techniques to weight lifting and provides many of the same benefits, but, while appearing quite similar, is a sport with different goals.
Most bodybuilders train for open competition, and their goal is to maximize muscularity and minimize body fat, as opposed to a weight lifter who doesn't care as much about how he looks, or she, for that matter, than how much weight they can lift.
Competitive body builders have from 2% t0 4% total body fat. A weight lifter, on the other hand, is primarily concerned with increasing strength and stamina, and is not too concerned with total body fat.