There is a difference, but it's a bit subtle.
With Tie::RegexpHash you set your hash keys to regular expressions and then look them up using fixed strings.
With Tie::Hash::Regex you set the keys to fixed strings and then look them up using regular expressions.
In this case, it looks like Tie::RegexpHash is the way to go.--
"The first rule of Perl club is you do not talk about
-- Chip Salzenberg