If it said Shimano 11 speed, then it's 11 speed.
I think he's asking if mtb cassettes are a different spacing or something.
Nah, the only exception is the Shimano 11 speed 11-42 MTB cassette which designed to fit on 10 speed hubs (and 11 speed too with spacer).
@Aches started
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If it said Shimano 11 speed, then it's 11 speed.