Hi Lodger,
It does say Glasgow on the 1881 yes but the 1911 says Wishaw.
I think in 1881 what might have happened is in 1881 he was asked where he was from by the enumerator and said Wishaw. The enumerator probably not knowing where that was asked and John probably said near Glasgow.
It's the only explanation I can think of for the difference
Best Regards
Alan