There is no difference between fur and hair; it is all just hair. Most refer to animal hair as fur, while referring to our own hair as just hair. However, hair and fur are chemically indistinguishable, both made up of keratin.
Human hair does not grow forever nor does animal hair/fur,
although the length of the growing cycle can be longer or shorter
for both. Various mammals have different growth cycles for their
hair than humans do. Cat hair seems to stop growing at a
relatively short length, similar to the growth rate and length of
the hair on a human’s arms and legs.
The maximum length of hair on various parts of a body is entirely
determined by genetics and varies widely from person to person and
animal to animal.
A cat’s whiskers are just hair, though these hairs are attached to
special nervous system connections allowing them to work as
A Porcupine's quills are extremely enlarged hairs.
Incidentally, shaving does not make your hair grow back
thicker, stronger, or faster. It has been proven by numerous
studies that shaving has absolutely no effect on hair growth
rate or shape