Well, Common Lisp is Lisp, Racket is Scheme, they are different. This perpetual confusion is just useless. Let's call things by their names. You don't call C++ C or php perl, right?
Racket is Scheme.
Scheme is Lisp.
SBCL is Common Lisp.
C99 is C.
C++0x is C++.
C++ is C.
Clang is C99.
Do all the lines seem correct?
LISP 1.5 is like C
Common Lisp is like C++
Scheme is like Objective-C
(ignoring all the other Lisp dialects that have fallen by the wayside: Maclisp, Interlisp, ZetaLisp)
I also agree, that Racket is not Scheme, it's a new language. But I stand, that Common Lisp is still a Lisp. Lisp 1.5 would be BCPL or B :) (Why? Because C is in active use, while Lisp 1.5 isn't, so your analogy isn't quite correct)