I can't answer this 100% but there are batch difference variations between floats which may or may not relate to release.
The problem is that while pearly Surf Rider was being sold in the US and Canada and maybe other places, regular Surf Rider was being sold in the UK. And so production logically would be for both those releases at the same time.
But because Surf Rider (regular) came out in the US etc earlier than in the UK/Europe, there are likely to be differences between batches produced.
Some floats have one line of text on the bottom and some two, I seem to remember, but am not sure specifically with Surf Rider.
I think it is basically impossible to prove a colour variation relates to a specific pearly/non pearly release for any of the baby sea ponies. It's more about the timing of production.