The Manx wool in light brown is the most voluminous, the grey Gotland fibre is smooth and straight and thus rolls up quite tightly, and in between the trusty brown Eider wool - which comes out a bit darker on this picture than it actually is.
Just like they are different in density when rolled up into a ball, they also feel very different. And I'm always stunned by the readiness of the Gotland wool to felt even though it feels so smooth and slippery. I think it's the felt-happiest wool that I have ever seen...