Question

How EM waves carry information.

Answer 1

It's actually the variation in the EM wave that carries information. a constant EM wave just say's I'm here.

Answer 2

what makes EM waves different from Photons.

Answer 3

Any "wave" or "electric current [computers] can be made to carry information by regulating it in some what. In the case of radio waves [RF], this is commonly done by changing the frequency [FM] or the amplitude [AM]

Answer 4

There is not difference between an EM wave it's corresponding Photon, They generally only consider Photon's at higher frequency because it's then when the energy is significant.

Answer 5

a photon's energy is plank's constant times frequency