What is the difference between “keyword” and “reserved word”?

Question

What\'s the difference between a keyword and a reserved word?

For example, in the proposal for concepts in C++ one can read the following statement

Answer 1

Just to show that the distinction is very meaningful:

Not in all languages are all keywords reserved words. In Fortran it is possible to do this:

if if then then else else

In this case, the keywords are not reserved, but depending on context can be interpreted by the compiler as variables.