Displays in the past were CRT (cathode ray terminals) displays, but laptops and most standalone displays are now LCD displays. LCD technology allows the display to be very thin, and is one of the things that make laptops feasible. It is now difficult to buy a new CRT display, although there are still a lot of older ones around. CRT displays are considered better for fast gaming, because of the way they handle movement. LCD screens take appreciably longer to refresh their screens, and for a gamer, a 5 MS lag can slow the pace of the game or prevent them noticing a change in an online game. There are now LCD screens with as little as 2MS lag time, and it is expected to improve.
LCD screens are also space savers, and can be wall mounted at need. Some stand alone displays can tilt a pivot, going from landscape mode to portrait mode, which was not possible with a CRT display.
A clear distinction between laptops and desktop computers is that desktops need a display and a keyboard, at a minimum, whereas the laptop has both built in.
Most computers are now able to support more than one display, so if you have your laptop sitting on your desk, you can usually connect a free standing display to it for more graphical real estate, as well as adding additional displays to a desktop. Specialized connectors are used to attach the additional displays.