This page will explain the different coat types in rats. A Coat type is a gene that effects the texture of the coat. It has nothing to do with color or pattern. 

-Note on coat types, all of these genes can be mixed together on the same rat in different combinations. I am not going to post pictures of all the possibilities.

The only exception is the 3 types of Hairless. They are either one or the other visibly, but can carry the others.

This is the wild coat type. No frills just straight hair & straight whiskers.

Curly Hair, curly whiskers. Males curl better than females. Additionally Agouti curls better than all other colors.

Not to be confused with Rex. Velveteen's are often mistaken for Rex but its actually simple to tell them apart. Velveteen have a wave to the whiskers not a curl, and the fur is thick and when you blow on it it you cannot see the skin. Its like blowing on a cotton ball. Rex are curly and you can easily blow on them to see the skin. Males curl better than females.

Hairless come in several varieties.

One is hr/hr which is mostly hairless with a little short curly hair on the nose, feet and small amount on the lower legs and short curly whiskers. You see them more times than any other.

Another is fz/fz which is the fuzzy variety. Fuzzy body and short curly whiskers.

And nu/nu. Nude. Totally bald and no whiskers. They look like a rubber chicken.

Fuzzy hairless. fz/fz. Fuzzy Hairless have a this velvet coat. It looks like they are wearing jammies.

Nude hairless nu/nu. Nude Hairless literally have no hair and no whiskers. These are harder to find.

Harley is the long haired rat.

There are multiple types of Satin. This is The AFRMA Satin. Its got a longer coat with long straight whiskers that go backwards toward the face. There is another gene people are calling Satin that you see these days, but its coat is not as nice as this one. These stay long the new ones get short hair as they age. They are 2 different genes. To each his own pick the one you like best. Also Satin in rats is not to be confused with Satin in mice. They do not look similar. Mice are very shiny. Rats not so much.

Silvermane is often mistaken for a color. But is now thought of as a coat type. It adds silver hairs that color change in a patch pattern as the rat molts. Very pretty. The hair is translucent and shines. It is very, very soft. It can be on any color of rat.

Angora is genetically Harley, so its long coated, with a recessive curl modifier. Also super soft. Angora are many times born looking like a Harley and then curl late, sometimes much later into adulthood. Sometimes they start to curl around 4-5 weeks old.