Racket is a single extensive implementation (maybe two versions of itself, the old one and the new one updated with bits from Chez Scheme). Common Lisp is a la

Racket is a single extensive implementation (maybe two versions of itself, the old one and the new one updated with bits from Chez Scheme). Common Lisp is a language standard with multiple (very different) implementations. SBCL is a native code compiled Lisp with type inference. ECL compiles to C or byte codes, with an interpreter. LispWorks and Allegro CL are commercial Lisps with IDEs and GUIs. CLASP integrates with C++. There are a bunch of other ones. Common Lisp isn't an academic product.