Answer:
The speed of sound is the speed at which the mechanical waves of sound travel, this speed is 343.2 m/s in our atmosphere.
In the other hand, the speed of light is the speed at which the electromagnetic waves (like photons of light, radio waves, etc) move.
This velocity is equal to c = 299,792,458 m/s in a vacuum, and in our atmosphere is almost the same number.
One interesting thing about this velocity is that is a constant, the speed of the light is the same in every system (this means that you will measure the same light speed if you are in the Earth or in a spaceship that travels at 10000m/s)
Now, you can see that the speed of light is a lot bigger than the speed of sound. This means that when there is thunder, the light produced reaches faster to you than the produced sound (because the light moves faster)
