Strength training is a program of exercises that increases muscle strength and endurance. Strength training is not necessarily the same thing as power lifting or even weight lifting .
While power lifters use heavy weights to build large muscles, people who strength train may use lighter weights or resistance and multiple repetitions.
You can do strength training with weight machines or free weights. But you can also do it with resistance bands, ankle or wrist weights, or using your own body weight as you would with a pushup.