I usually ride a little harder or at least faster in the morning. My rides long enough I'm going to sweat no matter what. I want to ensure I get there with plenty of time to cool down and change before official start of business. However I also want to sleep in as late as possible. Haven't really analyzed why, but the ride home is typically at least 1 mph slower. Maybe my legs are a little more tired, maybe a little less motivated, maybe a little more headwind, maybe net up hill. It's generally rolling hills the whole route. Likely more than one on any given day.