The terra terrane was thought to be landmass, and the maria terrane was thought to be the Moon's ocean, although this is now known to be false. The maria terrane is lower in elevation and younger in age than the terra terrane, and was formed by lava.
The terra terrane was previously considered a landmass on the Moon, while the maria terrane was thought to be an ocean; however, this understanding is now outdated. The maria terrane has a lower elevation and is of more recent age than the terra terrane, having formed from lava.