John's age was the crucial bit of missing information, as that probably cuts out 3 of the Georges, who were born 1811-1817. The remaining George is:
Frogs Abbey, Wimblington
George Fisher head marr 68 Farmer 11 acres born Wimblington
Mary Fisher wife 67 b Wimblington
Jabez Neville visitor 3 scholar b Wimblington
In 1841 this is probably the same family
In the Town, Wisbech Rd, Wimblington
George Fisher 60 cattle dealer
Mary Fisher 55
George Fisher 25 cattle dealer
John Fisher 20 ag lab
Sarah Fisher 20
John Fisher 10
Mary Fisher 35
A definition of jobber which I found by googling is "a buyer in quantity to sell to others". A dealer?
Instructions to enumerators in 1841 were that ages over 15 should be rounded down to the nearest 5 below. So ages under 15 should be actual. But there do seem to be a suspicious number of 10s and 5s in Wimblington and I wonder if the enumerator got a bit carried away and rounded down more than he should have done. It would probably need a bit of research on other families comparing census ages with the baptism index to see if this theory stacks up. If it does then the 10 year old John could actually be 14.
The next problem is sorting out relationships in 1841. As there is an elder John it seems to me as though the 25 year old George (actual age 25-29) might be the father of the younger John - although this wouldn't work if John was actually 14!
Of course John might have lied about his age on marriage and then kept up the pretence on subsequent censuses, particularly if his wife was a bit younger than he was.
Hope this helps
Regards
David