Since Hannah did graduation portrait sessions for four hours and family portrait sessions for the same amount of time, we know she has a fixed amount of time for both types of sessions. However, since she did not do as many family portrait sessions as graduation sessions, we can infer that the average time spent per family portrait session is likely longer than that spent per graduation portrait session.
As she will have the same number of sessions for both types tomorrow, if the time per session remains consistent with what it was today, she will likely finish the graduation portraits in less time because she can complete more sessions in the same time frame compared to family portraits.
Therefore, the answer is that Hannah will likely finish the graduation portraits in less time.