Lisp is either a family of language families (Lisps, Scheme, Logo, ML, MDL, JavaScript, Dylan, Racket, R, ...)
or
a more narrowly defined family of languages (often recognizable because they identify as Lisp in their name) and based on the core from Lisp 1: Lisp 1, Lisp 1.5, BBN Lisp, Interlisp, Maclisp, Franz Lisp, ZetaLisp, Le_Lisp, EuLisp, muLisp, Common Lisp (a standardized language), Emacs Lisp, Standard Lisp, ISLISP (a standardized language), ...
You'll find often in the Scheme literature Lisp described as a different, but related/derived, language (more symbolic, less functional, more procedural, procedural macros, less clean, less systematic, more dynamic, ...). Scheme is seen more functional, more lexical binding, less procedural, more minimal, one namespace, cleaner, ...).