Working from home means:
*You never leave the office. When you are home you can always work, but you are also never truly away from the work.
*You can never leave behind the home environment to be in one devoted exclusively to work. Why do people go to writers' colonies? To get away from home.
*You don't have all your work materials in one place, since you have to bring them home, and might forget some of them.
*Time is elastic. For example, it is 9:46 and I am at home. Am I working? I'm not sure. I've done some work related things this morning, but I am not fully committed yet.
Like virtually all academics, I do some work at home, but I don't necessarily see this as ideal. It is great for night owls and super early risers. If working at home were that great then my colleagues who are rarely at the office would have published two more books each.