General ambient lighting
You know the ceiling light that came pre-installed in your apartment, the one whose uniform but utterly unremarkable light seems somehow both too dim for reading, and too glaring for parties? That would fall into the general ambient category. Recessed track lighting, fluorescent ceiling lighting, and those cheap halogen floor lamps that are such a staple of dorm life are other examples of general ambient lighting. The advantages of this sort of lighting are that 1) a few sources of general ambient lighting usually come built-in to the house/apartment, and 2) these sources can cast a moderately bright level of light over a fairly large area. Adding more sources of general ambient lighting can brighten an entire room, making small rooms appear larger and dark-walled, dark-floored spaces feel a bit cozier. They also even out the lighting in a room when you’re watching television, which is a good thing, considering that the glare of the boob tube in contrast to pitch black surrounds can strain your eyes and cause headaches. Because these light sources illuminate over a large space, however, they give you little control over any areas in a room that you might especially like to highlight (a photograph, a painting, a sculpture, your bookshelves). They also never seem to provide quite enough light when you’re trying to perform tasks such as reading a book, writing a letter, making a sketch, or working on some craft project.

Task/Spot lighting
Task/spot lamps, on the other hand, provide very bright, very focused light that can be aimed to illuminate specific areas of interest in a room.  A task/spot light is generally a lamp whose bulb is semi-enclosed in a reflective casing and whose head can be aimed in various directions. Desk lamps, spotlights, floor lamps and track lamps with adjustable heads all belong in this category. 

When evaluating your lighting needs, think about where you sit in the room when you’re doing those tasks that require good lighting. If you’ve got a favorite comfy armchair where you like to curl up and read, it would make sense to place a lamp with an adjustable head right next to you, so that you can aim the light to fall directly over your book. Your worktable too will require either a good desk lamp (lamps with halogen bulbs are great, since they provide a clean, white light that’s quite bright), or a bright hanging project lamp (you’ll want something that reflects the light down, rather than a hanging lamp that encloses the bulb in a translucent shell). Any room in which you’ll be spending large amounts of time at night will require some sort of task/spot lighting … you don’t want to go blind straining to make out the words in that novel as you struggle to read by insufficient light, now do you?