Is it true that lifting heavy weights for a short period of time makes you stronger but lifting light weights for longer makes you more toned?

To be honest, these 'General Rules' are not based on reality. Every person is unique in their body and how it responds to different training, hence why their are so many conflicting idea's on the best workouts or training regime's.

Trying different workouts for yourself would be the key and find out what works best for YOU, to get the results you want to achieve. Along with workouts or training, diet and sleep is something of utmost importance to any athlete. Your diet will be something you will have to experiment with to yield the greatest results, again depending on what you want to achieve.