My g/g/grandmother was born in Mountnessing (essex) and on all her census entries this is what she has stated, however on 1 she has said Ingatestone (essex).
Having taken the time to go and get my injections updated and have my passport stamped I dared to take that darkened route to the other side of the deep and dangerous Thames from South London (Plumstead).
Well, I found that Mountnessing is a small village (I saw only a row of 4 shops, 1 of which was closed) but Ingatestone was the next large village/market town, was bustling with shoppers. They are only about 1/2 mile apart and if someone built a few houses inbetween they would be the same town. (Oh and the butchers was amazing - bought quite a bit of meat etc. there. People seemed to be coming from miles around to visit this one little shop).
I also think that Ingatestone was the registration district at the time, so yes she was born in Mountnessing but was registered in Ingatestone.
It might be useful when people change where they were born, to see if the different places are actually quite near to one another. I have done this by googling a place name, looked at any maps etc. and have found this to be the most common reason for differing place names.