On Android 4.1 (Jelly Bean) and higher (KitKat and Lollipop) devices, there's an option to have a "standard" notification or a "Rich" notification. The standard notification is a one-line notification, basically what Android has had for some time. The rich notification is an expanded notification with more information. If you turn the rich notification on/off and look in the device's notification area, you should be able to see the size difference between the two.
Some people prefer the rich notification since it includes more info, but some prefer to have it take up less space in the notification area as they want room for other notification items.