Sure, but all of these four are keywords, and not functions - this is what makes them special.

But in the context of parsing, they are not really treated that special from (prototyped) functions, so there is no difference in that sense. Well - I'm not sure whether it's possible to pass a label to a function. My naive approach doesn't pass strict:

use strict;
sub bar($) {
    print shift
};

FOO: {
    bar FOO;
};
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