Offray & Schiff are two different brands of ribbon. Schiff offers 80 colors of the grosgrain ribbon--these colors haven't changed in quite a while. Offray continually discontinues and introduces new grosgrain ribbon colors--they change frequently. Fortunately, I have many resources and can usually find recently discontinued colors. Sometimes the names of the colors are used with both brands, but sometimes they aren't the same "shade." (Currant, for example--Offray Currant is much brighter than Schiff Currant) This is why some colors are listed twice.
Above is what I found on a Google search. I hope that will answer your question.
Personally to get the best prices on ribbon, I would stick to the internet sites. Hopefully these places do send ribbon to the UK. If you do not know which sites to go to already let us know and we will direct you in the right direction.