Why is speed class B when ecstasy is class A?

Now, i didnt know much about speed so i've just been doing some research and everyone seems to be saying that speed is alot worse for you than ecstasy (obviously neither are good for you). In this case, why is speed class B and ecstasy class A? And why is ecstasy class A anyway?

: http://alcoholdrugstreatment.info/why-is-speed-class-b-when-ecstasy-is-class-a