It helps if you know what to look for, and to decide which features are most important to you. Some cameras are capable not only of capturing still images, but sound and even video. Some high-end cameras can use interchangeable lenses. Entry-level cameras typically set shutter speed, focus, and white balance automatically. Higher-level cameras have the option of letting you manually override some or all of these settings for more creative control.
Image quality is determined by resolution and color depth.
In digital, your worries about film are replaced by your worries about storage. Cameras usually enable you to store images at high, medium, or low resolution, which use up commensurately less space. One feature offered by many digital cameras is an LCD viewfinder panel in the back of the camera. This enables you to see the actual image you've just taken, and decide whether you want to keep it or reshoot. The big problem with the LCD is it uses up a lot of battery power, which is why digital cameras are notorious for burning through batteries.