How can eval-when-compile and eval-and-compile have different behavior if their definitions are identical?

From byte-run.el:

(defmacro eval-when-compile (&rest body)
  ;; ... documentation string omitted ...
  (declare (debug (&rest def-form)) (indent 0))
  (list 'quote (eval (cons 'progn body) lexical-binding)))

(defmacro eval-and-compile (&rest body)
  ;; ... documentation string omitted ...
  (declare (debug (&rest def-form)) (indent 0))
  (list 'quote (eval (cons 'progn body) lexical-binding)))

How can eval-when-compile and eval-and-compile have different behavior if their definitions are identical?

From byte-run.el:

(defmacro eval-when-compile (&rest body)
  ;; ... documentation string omitted ...
  (declare (debug (&rest def-form)) (indent 0))
  (list 'quote (eval (cons 'progn body) lexical-binding)))

(defmacro eval-and-compile (&rest body)
  ;; ... documentation string omitted ...
  (declare (debug (&rest def-form)) (indent 0))
  (list 'quote (eval (cons 'progn body) lexical-binding)))