Recently ubuntu has switched to a new shell called unity which is built on the top of gnome 2.x series while the traditional gnome has migrated to the new incarnation of gnome called gnome 3 and it sports a different shell from the traditional gnome 2 series and unity.
Actually there is not much difference between the user interface of gnome3 shell and unity. But unity uses compiz as window manager while gnome3 relies on mutter. Ubuntu wanted to use compiz but gnome developers preffered mutter. That is the reason why ubuntu developers has created unity based on compiz.
Actually there is not much difference between the user interface of gnome3 shell and unity. But unity uses compiz as window manager while gnome3 relies on mutter. Ubuntu wanted to use compiz but gnome developers preffered mutter. That is the reason why ubuntu developers has created unity based on compiz.
