1851 London Township-St Patricks Rural Ward & 1878 London "East" just east of the city limits - are these 2 areas the same and known as Nilestown today?

No. St. Patrick's rural ward extended from Highway 4 (Richmond Street) on the west to the West Nissouri Township boundary on the east and Telfer Road (now Nine Mile Road) in the north to the North branch of the Thames River in the south. London East was the area east of Adelaide Street, and Nilestown is located in North Dorchester Township -- a bit of a distance away