Both pinto and paint (note the lower case "p") are still commonly used terms in many areas of the world to describe a spotted color pattern.
But both Pinto and Paint (note the capital "P") also are used to refer to horses registered with specific registries-- The American Paint Horse association (APHA) and the Pinto Horse Association (PtHA).
Both associations have rules and limits-- Paint being much more restrictive of bloodlines and more specific for one type than Pinto.
Here are links to both associations--
Paint-- APHA.Com - History of the Breed
(also check the links on the right of this article for more info)
Pinto-- PtHA ? Registration
(with this new addition to their allowable registries-- http://www.pinto.org/information/utility_PR.pdf