I don't really understand why they have two pie charts. They are saying in the back up notes that heating, lighting etc in homes is an indirect emission and not included in the pie chart you chose. The second pie chart is the one that IMO reflects reality.

Yeah, one of the pie charts breaks out "electricity" into its own sector, while the other assigns electricity-related emissions to the other sectors based on their electricity use. Which is why the "buildings" wedge looks a lot bigger in the other chart: buildings use about 3/4 of US electricity.