What is the difference between function template and template function?
The term "function template" refers to a kind of template. The term "template function" is sometimes used to mean the same thing, and sometimes to mean a function instantiated from a function template. This ambiguity is best avoided by using "function template" for the former and something like "function template instance" or "instance of a function template" for the latter. Note that a function template is not a function. The same distinction applies to "class template" versus "template class".