No it's not! It isn't related as those 2 metals are!
It's just a stupid marketing move.
Well, that is true, in the end they are the same breed, they just differ on a few points. Though it does follow the pattern in that Litecoin would overall be worth less per full coin but many more of them, so not as rare as Bitcoins are, silver to gold in a sense and the exchange prices will probably always reflect that, assuming somehow Litecoin doesn't win the end (it could, you never know). I think it is an accurate way to explain them to someone who doesn't know what Bitcoin or Litecoin are without a 2 hour long conversation on why they are different at the technical levels.