What is the difference between cat fur and cat hair?

Yup! I was trying to find the answer for the above question..and i found dis useful article to share. Enjoy reading! I even provide a picture to try illustrate it better.. =) (of coz the model is 1 of my cat..)

Actually, all mammals have hair, from humans to whales, to pigs and elephants, to cats, dogs, and monkeys. But the hair has a different appearance, feel, and purpose, depending on the development of the individual species.

But Not All Hair is Fur
Technically speaking, however, the term fur is generally confined to mammals with very thick body hair. (Humans lost ours through evolution, if one believes Darwin.) With cats, the terms are almost always used interchangeably, although with some "hairless" breeds, the Sphynx in particular, the short, downy stuff that is almost invisible is usually called "hair."

But with most cats we use terms like "hairballs" to describe the fur cats swallow and then hack up, while we affectionately refer to our cats themselves as furballs or furkids.

Personally, I think of "cat hair" as individual and "cat fur" as collective, e.g., a cat hair is what I find on my black sweater. There may be many of them, but they are not all massed together like fur is on my cat. When grooming my cat I may either "comb his hair" or "brush his fur."

To complicate things further, breeders often describe the overall appearance of a cat's fur as its coat. You will see this term used almost exclusively in breed standards, but you will also see "hair" mentioned, as in longhair or shorthair breeds or divisions.

Different Types of Cat Hair and Coats
Like all hair, cat hair originates in the epidermis (under the skin), and the type of hair determines the structure. There is a muscle next to the root, just under the skin, that is extremely sensitive to temperature. In cold weather, or when a cat is frightened or alarmed this muscle contracts, causing the attendant hair to "stand straight up," causing that "Halloween cat" look that is so familiar. Cats may have from one to three types of hair in their coats, referenced sometimes as "double coat," or "triple coat," plus those distinctive whiskers, which are also hairs.

Whiskers (Vibrissae) @ misai kucing..hehe~ 
Long, thick, tactile hairs extending from the sides of the muzzle, above the eyes, the cheeks, and at the outside of the lower legs on cats. Whiskers are extremely sensitive, and play an important role in cats' ability to gauge openings, find their way around in total darkness, and they may even contain a scent-sensing ability. Whiskers are also an important factor in revealing cats' body language.

Guard Hairs
The longer, stiffer hairs that extend out past the "base coat" (awn hairs). These are the hairs that usually determine the basic color of the cat. Guard hairs help in retarding water to keep a cat dry.

Undercoat, also called "Down"
Softer, fluffier hair that provides warmth. This is the hair that tends to mat if a cat is not groomed regularly.

Awn Hairs

There are several different definitions of awn hairs, depending on the breed of cat, but awn hairs usually form the basic coat. In some breeds, the (finer) awn hairs may be the same length as the guard hairs, while in other breeds, such as the Manx, the guard hairs are longer. 

Vellus
Sparse, baby-fine hairs, such as those found on the Sphynx cat. (Humans also have vellus on all but a few body parts.)

Curly Hair vs Straight Hair
As in humans, curly hair in cats has flattened shafts while straight hair has round shafts.

Cat Hair and Allergies
The allergen cats carry is a tiny protein particle called Feld1, which is found in cats' saliva. They transfer it to their hair when grooming, where it dries into microscopic flakes, commonly called dander. Very long or thick cat hair will hold more dander, which is where the misconception that the "hair" is the allergen arises. Dander can also be found all over the house: in the air, in bedding, and in carpets and drapes. The good news is that in many cases, allergies to cat dander can be controlled.

Taken from --> http://cats.about.com/od/faqcatcare/f/catfurvscathair.htm