Legislative day versus Calendar day
A legislative day extends from one adjournment to the next. The House normally ends its business at the end of a day and adjourns, so its legislative day generally corresponds to the calendar day. The Senate often recesses, rather than adjourns, at the end of the day in order to avoid certain required routine business that begins a new legislative day. Thus, the Senate's schedule can be made up of a handful of legislative days even when it has been meeting for several months.