The difference is huge. In warm months my water/sewage/gas bill is $50-60; in cold months we use a gas furnace and the highest I've seen that bill is $350, but generally it's around $300 in the cold months. Like I've said before: after hearing that some neighbors pay twice that, I will be content with my $300 bill.
When I tell people that we keep our heat setting around 64*, they balk. The lowest they set theirs is 68* and many keep it closer to 70-74*. One family I know that does this wears t-shirts and no shoes around their house most of the winter and I think that says a lot. I often wear 2 layers, socks, slippers, and keep throw blankets piled around for when we'll be sitting at the computer or to watch a movie in the living room. Or we'll all pile on my bed on top of or under the heated blanket and play a game or watch a movie in my bedroom. I rarely get complaints from my family about the house being cold.