Complex sentence: The Lisp dialect used in Emacs differs substantially from Common Lisp and Scheme, dialects used for applications programming, mainly because Emacs Lisp uses dynamic rather than lexical scope.
Split into simpler sentences: The Lisp dialect used in Emacs differs substantially from Common Lisp and Scheme, dialects used for applications programming. Chiefly, Emacs Lisp uses dynamic rather than lexical scope.