my @apps = split ' ', $form{'AppName'};
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The difference is in how they treat leading spaces. See split

$ perl -le'print 0+( @a =            qw( a b c ) )'
3

$ perl -le'print 0+( @a = split /\s+/, " a b c " )'
4

$ perl -le'print 0+( @a = split " ",   " a b c " )'
3
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Thanks everyone!