If your bedrooms are upstairs, at night you might be running heat a lot less since some of the heat from the first floor rises up to the second. If you have carpet, that can create a warmer area at the floor, closer to where your beds are. So you might not need to heat things as much, or to as high a temperature to feel comfortable.

I lived in an apartment where the floor was poorly insulated. When a new neighbor moved in downstairs that heated their bedroom more aggressively at night, my heating bill went down because the heat rising from below made it less necessary to run my own heating as hard.

It might also be the difference in electricity cost. Especially with tiered rates, you can easily find yourself moving into a higher tier where every kW is significantly more expensive than in the previous tiers. PG&E in the SF Bay Area charges between 43 and 60c/kWh. A 2kW heater is going to cost about $1/hr to run , so if you're working from home, have little kids it gets expensive quick. And in the middle of a NY winter, with a poorly isolated apartment, you might well be running the heat in some capacity pretty much 24/7.