为了在Common Lisp中使用它们，请参阅Rainers的详细答案。简要总结一下：

form的HyperSpec条目：

form n. 1. any object meant to be evaluated. 2. a symbol,a compound
form,or a self-evaluating object. 3. (for an operator,as in
<<operator>> form'') a compound form having that operator as its
first element.A quote form is a constant form.”

expression的HyperSpec条目：

expression n. 1. an object,often used to emphasize the use of the
object to encode or represent information in a specialized format,
such as program text. The second expression in a let form is a list
of bindings.'' 2. the textual notation used to notate an object in a
source file.The expression ‘sample is equivalent to (quote
sample).”

因此，根据HyperSpec，表达式用于(文本)表示，而表单用于要评估的Lisp对象。但是，如上所述，这只是在HyperSpec(因此Common Lisp)的上下文中这些术语的定义。

然而，在计划中，R5RS根本就没有提及形式，仅谈论表达。 R6RS甚至给出了一个几乎听起来像上面正好相反的定义：

At the purely syntactical level,both are forms,and form is the
general name for a syntactic part of a Scheme program.

(谈论(定义…)和(* …)之间的区别。)