These are closely linked, but all a bit different.

There are 3 types of strength:

Static

When you exert a force against an immovable object, muscles stay the same length

Useful in activities such as arm wrestling and rugby scrums

Explosive 

When you exert a force in short, fast movement

Useful in the javelin and high jump

Dynamic

When you apply a force repeatedly over a long period of time

Useful for press-ups and cycling

For speed, you need fast reaction times-the time it takes you to respond to something (a starter’s gun, or a pass in football), and fast movement times-the time it takes you to carry out a movement (a shot on goal, or 100m sprint)

Power is strength and speed combined.