Well there's no way to have lightning without thunder since Thunder happens as a direct result of lightning.
The Thunder is caused by the rapid expansion of the air surrounding the path of a lightning bolt.
You can count how far away a storm is though by counting how many seconds until you hear the thunder after seeing the lightning.
If it takes 5 seconds to hear the thunder after seeing the lightning then the storm is one mile away from you.
Also Thunder can be heard up to 25 miles away, and lightning strikes have been documented to occur as far as 25 miles away from thunderstorms.