The pink is a solid dye - it comes in a little plastic container and you have to shave it off and mix it into the soap until it melts. The purple is a Labcolour dye - diluted, Royal Purple. You can see the difference.
Although there was nary a spot of unmelted pink when I mixed and poured it, it obviously solidified when the soap cooled. I think it looks kind of neat, but it's not something I want for every soap.
Why would you want to choose a solid dye? It's far cheaper than the liquid dyes, and it lasts forever. You don't need much to colour a large batch of melt & pour soap. And it comes in some different colours - I specifically bought the burgundy (the pink above is supposed to be burgundy). But it is a pain to think your dye has melted, only to see it has solidified to give you this mottled look. Having said that - it does look kind of neat!
So if you're a newbie to melt & pour soap making, I'd suggest sticking with the liquid dyes because they are more predictable!