The current wording in the standard makes it hard to discriminate the difference between a "call wrapper" as defined in [func.def]/5+6:

5 A call wrapper type is a type that holds a callable object and supports a call operation that forwards to that object.

6 A call wrapper is an object of a call wrapper type.

and a "forwarding call wrapper" as defined in [func.require]/4:

4 [..] A forwarding call wrapper is a call wrapper that can be called with an argument list. [Note: in a typical implementation forwarding call wrappers have an overloaded function call operator of the form

template<class... ArgTypes>
R operator()(ArgTypes&&... args) cv-qual;

— end note]

Reason for this lack of clear difference seems to be that the wording adaption to variadics and rvalues that were applied after it's original proposal in N1673:

[..] A forwarding call wrapper is a call wrapper that can be called with an argument list t1, t2, ..., tN where each ti is an lvalue. The effect of calling a forwarding call wrapper with one or more arguments that are rvalues is implementation defined. [Note: in a typical implementation forwarding call wrappers have overloaded function call operators of the form

template<class T1, class T2, ..., class TN>
R operator()(T1& t1, T2& t2, ..., TN& tN) cv-qual;

— end note]

combined with the fact that the word "forward" has two different meanings in this context. This issue attempts to clarify the difference better.