Sentence:  The differentiation however <WSD>is</WSD> not very much greater , as shown by the fact that Athabascan shows 3.46 stems per meaning slot as against 2.75 for Yokuts , with a slightly greater number of languages represented in our sample : 24 as against 21 . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)