What is the difference between a Muscle and Classic car ?

[Ms Grumpy]

I was reading an article on the difference between a Classic car and a Muscle car in a major car magazine this morning. This article made me feel like it was going in circles, never really answering the question. What is the difference between a Classic car and a Muscle car.

I always thought that most "Muscle Cars" were produced between 1967 and 1972, with a couple major exceptions, one being given to the Mustang which started production in 1964 or 1964 1/2. But there was the GTO which was introduced in 1964 (I think), and I have read that many people considered the GTO the very first Muscle car.

So what to you consider to be a Muscle Car ?

And what do you consider to be the difference between a Classic Car and a Muscle Car.