If the difference didn't matter, we wouldn't have so many different lisps. Obviously the difference mattered enough to the people that created Common Lisp when Scheme already existed. Rich Hickey thought it mattered when he created a completely new Lisp instead of just porting Scheme to the JVM.

> If the difference didn't matter, we wouldn't have so many different lisps

Literally the opposite. We can make and use so many, because writing them is more or less the same. We can quickly throw together a new lisp for a new platform or such and use it without problem.