The difference in the amount of thermal energy in two modes: 1-using the conventional lighting schedule 2-lighting schedule based on daylight simulation

I simalated energy consumption in ladybug tools 1.6, with two types of lighting schedule: 1-lighting schedule based on Ashrae standard 2- the same lighting schedule based on Ashrae standard in combination with daylighting simulation results.
Results of cooling and heating energy in this 2 modes are different. Why results of these two types are different a little?!