What this boils down to is that what a breed standard calls a color may not be what I will call the color. I am trying to refer to both terms, but these can often be quite different. The reason why terms vary so greatly between dog breeds is because the standards were written by completely different people at completely different times. Also, sometimes the layperson will misinterpret what a color actually is. Here are some examples.
|A "red" Doberman is actually liver and tan|
|This "brown" mixed breed is actually a lightly masked sable|
Brown is a very similar conundrum to red. Though brown usually refers to the liver coloration (with or without tan markings) and that is what it should refer to in my opinion, it is sometimes also used to refer to sable or recessive red dogs. This can include sable with various skin pigment (usually black or liver) and dogs with or without black or the dilutes thereof in their coats (either as a mask or light sable overlay ).
|"Blue" Aussies are extreme piebald black and tan with roaning|
In my opinion, the term "blue" is one of the worst offenders when it comes to what it can include. The term blue really should refer to the blue/dilution gene, which turns black in a coat to a slate gray color. However, it can also refer to dogs with the graying gene (born black and pale with age), black dogs with the merle gene, or black dogs with ticking or roaning (which are born black and white and darken with age). All of these various forms may also have tan points. The dog seen at right will have been born mostly white in color.
|This "gray" Schnauzer is very pale red or "platinum" agouti|
|This "white" Dane is a double merle harlequin|
|This "fawn" Boxer is masked sable carrying extreme piebald|
This list is also not all-inclusive. There are numerous ways in which color terminology can be confusing. To avoid this, I am trying my best to be consistent so that the various GtG's can be more easily compared to one another.
All images are from Wikimedia Commons under creative commons licenses: one, two, three, four, five, six