Generally, yes. In a few cases, there's a difference. Binary bit operators, for instance.

  say "12" | "34";  # 36
  say  12  |  34;   # 46
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And you might think the following code won't give you a divide by zero error:

if ($num && $num =~ /^[0-9]+$/) {say 1/$num}
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but it will if $num eq '00'.

Devel::Peek is a tool that can tell you whether scalar holds a numeric value or not (look for the IV and NV flags).