Generally no, however you may want both, allow us to explain.
A Grounds Pass gets you into Melbourne Park, and allows you to explore the precinct, including outer courts, warm-up courts, food and drink outlets, brand activations, entertainment stages, John Cain Arena, Kia Arena and other arenas. If you have a Grounds Pass, you cannot enter Rod Laver Arena (RLA) or Margaret Court Arena (MCA), as these two arenas require a reserved seat ticket.
If you have a RLA or MCA ticket, this will also get you into Melbourne Park and then into your reserved seat in either arena. However, if you have a night session ticket, you cannot enter until 5 pm (earlier for twilight sessions), so if you did want to go earlier in the day to enjoy more tennis, you would need a Grounds Pass during the day, then your night session ticket on RLA or MCA would begin from 5 pm (you don't need to leave/re-enter).
If you have an RLA or MCA ticket for the day session, once the session finishes you will be required to leave the arena, however you don't need to leave Melbourne Park and you can stay for the remainder of the night and enjoy the attractions, outer-courts and plenty of things to see, do and taste!