perl: difference between use encoding 'utf8' and use utf8

`use utf8;` tells the compiler that the script is written 

in UTF-8. That's all it does.

`use encoding 'utf8'` tells it the srcipt is in UTF-8, 

its literal strings are in UTF-8, and STDIN, STDOUT, 

and DATA are in UTF-8.

$ perl -Mutf8 -e'print"\x{2022}\n";'
Wide character in print at -e line 1.
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$ perl -Mencoding=utf8 -e'print"\x{2022}\n";'
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