And the 1891 census:
https://www.ancestry.co.uk/interacti...cklabel=Return
William Jones Head M 56 Coal Miner Bagillt Flintshire
Sarah Do Wife M 50 Rhos Denbighshire
William T Do Son S 13 Do Do.
Sarah's year of birth is actually pretty consistent across those three censuses - ages 29, 40, 50 - it is William's which changes a lot. Since his birthplace on the 1881 census is given as Ruabon, it could be that that one was filled in by someone who didn't know much about him.