The first case is different from the others. Using warnings helps there:

$ perl -wle 'print <x>'
Name "main::x" used only once: possible typo at -e line 1.
readline() on unopened filehandle x at -e line 1.
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Using B::Deparse on the other three tells us that they use the same program structure:

$ perl -MO=Deparse -le 'print <x*>'
BEGIN { $/ = "\n"; $\ = "\n"; }
use File::Glob ();
print glob('x*');
-e syntax OK
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Using that snippet for your first case as well gives:

$ perl -MFile::Glob -wle 'print glob "x"'
x
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So glob treats the two first cases differently. The documentation says that it implements csh semantics. I guess that's why.