By contrast, Unity remains oriented towards a single screen unless you use virtual workspaces. For light usage, this setup is less confusing and tiresome; in GNOME 3, it can sometimes seems like you are changing screens every few seconds. However, on a netbook in particular, Unity opens many windows full-screen -- or near enough to make no difference. If you work with more than a couple of windows open at the same time, the effect is not much different than working in GNOME 3.
Where most people are likely to notice the differences between GNOME 3 and Unity is in their implementation of similar features.
For example, if you add applets to your desktop's panel, or application launchers to your desktop, one of the first things you will notice in both Unity and GNOME 3 is the difference in work flows. GNOME 3 does not include the option of icons at all, and, while Unity does allow desktop icons, its design steers users away from them. Both interfaces feature uncustomizable panels with little on them except a clock and a collection of app indicators -- that is, controls for sound, batteries, Internet connections, and personal information. GNOME 3 also uses the panel for a task indicator.
GNOME 3 and Unity also eliminate the traditional drop-down menu. Considering that almost all monitors these days are wide-screen, with more horizontal than vertical space, this decision seems logical, especially for interfaces that might be used on netbooks. Instead, both add a panel on the left side of the screen, often referred to as the dashboard in GNOME 3, and as the launcher in Unity. But, whatever the name, this new feature displays basic and running applications.
Of the two, Unity's launcher is the most flexible. Since GNOME 3's dashboard displays on a separate screen – no applications run on this screen – it does not need to auto-hide when a window needs its space, and in its current incarnation it is mostly uncustomizable. GNOME 3's dashboard also has the problem of shrinking to near illegibility if you open too many apps, forcing you to fall back on the mouseover help to identify the icons.
In contrast, you can customize some of the icons on Unity's launcher. The launcher also accommodates large numbers of open windows by showing a collapsed view at the bottom that opens quickly when you need to scan them. Unity's launcher also replaces a task indicator with small arrows to mark open applications. Although these arrows are easy to miss at first, they are an elegantly economical use of space once you are aware of them.
However, Unity's icon for virtual workspaces is perhaps too easy to overlook or work with. GNOME 3's panel for multiple workspaces on the right of the overview is much more efficient, at least until you open more than four or five workspaces at the same time.
At right angles to GNOME 3's dashboard is another menu across the top with items for open windows and applications, with sub-items that appear as large icons on the desktop and can be filtered by a variety of views or by a search window -- both of which are easy to miss on the far right of the desktop.
Unity, on the other hand, opens its application menu from its launcher (and, rather confusingly, refers to the resulting view as the dash). Unity's dash is filterable by categories, and includes a search field that is much easier to find than GNOME 3's.
However, Unity's sub-menus do have the annoying habit of displaying only a single line of items plus a link announcing how many items are not displayed -- even if there is only one. While shrinking icons to fit the space is obviously not a solution if dozens of other items exist, I can't help wondering whether an exception couldn't be made when only a few other items are available.
For that matter, you might question whether the change from drop-down menus is worth the effort by the developers or the trouble that users must take to familiarize themselves with it. In the efforts to avoid the menus overlaying too much of the screen, both GNOME 3 and Unity have created alternatives that cover the screen far more thoroughly than any drop-down menu. The result is easier to read for the visually challenged, but otherwise might be said to exchange one set of problems for its exact equivalent.
The same might also be said for the handling of windows, especially in GNOME 3. By default, neither interface allows resizing of windows beyond switching between their default size and maximizing them. Moreover, both use hot spots on the edges of their desktops to minimize or maximize, or tile windows. But GNOME 3 takes the extra step of eliminating title bar buttons to minimize or maximize buttons, forcing users to rely on the hot spots. Like the change in the menus, these changes seem to enforce an orthodoxy and limit user choice for no clear benefit.
hope i helped!