What is the main difference between free weights and a universal machine?

Answer 1

Free weights cost less money. People have used free weights on a weight bench and have not used a spotter. The free weights have fallen on them and killed them. A universal machine is more expensive. You can not drop a universal machine on yourself.

Answer 2

A machine will basically always hit certain muscles, not due to you but down to how the machine is made. However free weights allow you to hit a larger variation of muscles as it's not isolated.

It's best to use both as you will not be able to perform some workouts on a machine and visa versa. Remember to change up your workout every 6 weeks.