Ultracolour Plus is grainier for 2-20mm joint width and has the biggest range of colours. The FF is fine grain for 0-6mm and smoother for softer glaze tiles and is only available in just under half the amount of colours of the UCP. Both are flexible and contain the "drop effect" repellent, but only the UCP has the Bio-Block anti-mould additive.
Gone seem to be the days of people using fine for wall and wide-joint for floors. Seems to be minimum 2-3mm wide-joints all the way for almost anything, mainly for being a bigger range of colours and harder tiles being less prone to grit scratches.
