First of all I am not a color expert but have been studying pinto genes for years. I am very lucky to have a mentor that started the color site Refreshing to welcome page...
Before we go further I do breed Overo and pinto. But I always go for conformation first and color second. So now that that is out of the way :)
Paint---Paint is a BREED of horse. So for example a Shetland Pony cannot ever be a PAINT. A horse that is not registered with the Paint Association cannot be a PAINT. Its a pinto!
Pinto---Generic term to describe markings on a horse that is not a PAINT.
Tobiano---A TRUE Tobiano with no other pinto genes will have a colored head with no white. Also will have chest shield, color in the flanks and 4 white stockings with jagged edges. Will also have a split tail. BUT keep in mind those are kinda rare. Most will also have another pinto gene such as Sabino or Splash. Tobiano DOES NOT cause blue eyes. Tobiano can be very hard to pick out on a minimal expression horse. A "lightening" bolt down one side is a very common tobiano marking
Tobiano mare that also carries splash or frame. I know she has one or the other has she has one blue eye. I will be testing her for frame. But here is the classic lightening bolt marking. Also notice the roany spot by the hip caused by Sabino
Here is my stallion that was color tested postive for one copy of the Tobiano gene. He is also hiding splash. The clue that he's carryign splash is his odd big blaze. Many people thought I was nuts when I bought him because I knew from looking at him he was gentically Tobiano but I tested him to be sure. He is lethal white negative. See the jagged edges on the legs?
Frame or Lethal white---Again this is not a "disease" The frame or LW gene produces wild colored frame overo horses. But the horse is always carring other pinto genes at the same time. As long as you do not breed Frame to Frame there is no cause for concern. Frame causes blue eyes.
This is our stallion Feature. He is a visual black frame overo pony. He is also carrying splash and tobiano and probably sabino.
Splash causes more white on a horse and a classic splash will look like a horse dipped in white paint. What most don't realize is that splash can hide like my first stallion posted. Splash can cause blue eyes. There is not test yet for splash.
My splash mare that is also tobiano. Im also pretty sure she is homozygous for Tobiano but have not tested her yet. You can see how the splash covered up some of the Tobiano markings making her more white.
You don't hear much about this but I used to own a Rabicano stallion. Rabicano's are often mistaken for roans. As they mature they get lots of roaning in the flanks and have a skunk tail
There are now tests for 2 sabino genes but they are very good yet. Sabino causes roaning,face white and smaller white socks. It does not cause blue eyes. Many feel that sabino should not be called a pinto gene as it is seen on so many horses that are not gentically "pinto" For example the Budweiser Clydes. You can get a maximum sabino which will mimic a frame overo. If you have a tobiano with roany spots on the edges of the tobiano markings its sabino doing that.