From the standpoint of basic exercise physics weights and resistance bands have a lot in common. Both provide something for the muscle to work against beyond gravity. But the detailed differences allow them both to serve different goals.

A weight, whether in the form of a free weight or a stack on a machine gives you the opportunity to exert a varying degree of force. That makes it possible to tailor your workout to your level.

Weight training improves strength over time, while tuning the cardiovascular system which reacts naturally to supply muscles with what they need. As you build strength you are improving coordination, creating a stable body environment for joints and making the heart work, which improves overall health.

Resistance bands offer similar benefits, along with some of their own.

As you increase the amount of stretch, the band pulls back with greater and greater force. To get a feel for the amount of that force consider a highly stretched rubber band. It travels a lot farther when released than a limp one.

Resistance bands help increase bone density, as the body reacts to the strain by releasing biochemicals that add calcium. It's very indirect, but the effect is real, even while it's gradual. That effort increases the metabolic rate as the body supplies oxygen to tissues.

Beyond the valuable workout benefits there are convenience benefits to exercise bands, too. They're ultra-easy to store, since they'll fit into a drawer or on a closet shelf with no problem. Lightweight and ultra flexible they are even easier to handle than small dumbbells. And a lot safer.

In both cases - band or weight - the muscles have to work against forces directed against them. But now look at the differences in how those two types of force are applied. They tend to operate in different directions.

The difference in those two directions creates an opportunity to work different muscles in different ways. Both help enhance strength, but using both gives you a much wider variety. That leads, in turn, to a workout that is more comprehensive.

For those who are recovering from an injury, whether from a previous workout or more long term, an exercise band can be a little easier to use in some circumstances. You can insert a foot into the handle of a resistance band, then take up the other end with your hand. Or, you can use both feet to stretch the band. That gives a range of exercises it would be hard to duplicate with weights, unless you invest in some expensive equipment.

Free weights on the other hand, say in the form of small dumbbells, can offer a great way to do some curls even in a wheelchair. It's possible to use a resistance band that way, but it can be more difficult, depending on the type of injury you have.

Both methods have their strengths and weaknesses and the ideal workout program will incorporate both to get the best of both worlds.