Is there actually any difference between them other than the obvious one? I feel there must be as I don't think the cat has a preference based on colour.
On pondering this question further I submitted it to the Mighty Google, there to find even a dedicated area to debate the issue, along with umpteen other variations of my query.
If you know the definitive answer then this is the place to share it, thus alleviating me of at least one of my worries. Another being that there is no difference and I just like the girly colour... Along with: are they all made in the same place, is there a standard size (it looks suspiciously like it to me) and did Marlon Brando use them in his cheeks in The Godfather? Try it, they work a treat.