Fluids generally aren't composed of grains, where as cubes of ice are grains... More granularity typically means of finer grains... so smaller ice cubes are more fine grained, more granular. [0]

0 - Wikipedia: "The concepts granularity, coarseness, and fineness are relative..."

Yes, but note that your cited article doesn't talk about "more granular" or "less granular"; it talks about "fine-grained" and "coarse-grained".