Emilyjoy, a "warmblood" is generally accepted to mean particular breeds of horses, many of which were specific to certain areas (many of which were in Europe). They were developed to fit a certain type wanted for specific jobs. Many were heavier types meant to be classy coach horses. They were heavier bodied and had nice movement. Others were a lighter and finer type more geared toward the carriage trade. Over the years, they developed distinct "types".
However, when coaches and carriages went out of style, with the entry of motorized cars, the warmblood was in danger of dying out of existence. What saved them was horse sport. These horses found a home in the competitive ring and the race was on to develop them for this purpose. As a result, there was a change in what they were looking for in "type". The lines between the different breeds started to become fuzzier as they started changing.
In today's world, it is quite difficult to tell one breed from another. But, at least they have a distinctive hot brand, usually found on the haunch, that gives you a clue.
Here are a few examples of these breeds. Again, the name of the breed usually tells where the particular "type" was developed.
Trakehner Trakehner - Wikipedia, the free encyclopedia
Oldenburg Oldenburg horse - Wikipedia, the free encyclopedia
Enough of the German provences, let's see some national warmbloods....
Swedish Warmblood Swedish Warmblood - Wikipedia, the free encyclopedia
Belgian Warmblood Belgian Warmblood - Wikipedia, the free encyclopedia
See? This is just a minor sampling of the different warmblood breeds.