Classical has a few narrow definitions, including (1) of or relating to the ancient Greeks or Romans, (2) of or relating to a peak stage of a civilization, and (3) of or relating to European orchestral music of the late 18th and early 19th centuries. These aren’t the only definitions of classical. What’s important is that the term usually relates to fairly well-defined historical periods of culture and science.
Classic is broader. Its main adjectival definitions are (1) of lasting significance or worth, (2) typical, and (3) adhering to established standards of elegance or restraint. As a noun, it means an enduring work, and as a plural, with the (and usually capitalized—the Classics), it refers to the literature of ancient Greece and Rome.
Classical is usually uncapitalized, though writers often capitalize it when it refers to a specific movement. For instance, Classical music refers to music from a well-defined time and place, while classical music refers to most orchestral music.
You may remember Carter as a Hall of Fame catcher for the Expos and Mets and a signature player in the classic 1986 World Series. [Los Angeles Times]
Russell Maliphant’s new work opens, appropriately enough given the artist who inspired it, like a fin de siècle fantasy of classical Greece. [Evening Standard]
Alba teamed the black and turquoise frock with opaque tights, classic black heels and a white and black clutch bag. [Stuff.co.nz]
El Sistema, Venezuela’s program of social uplift through classical music, has received more attention over the last few years. [New York Times]
Crews arrived to find a classic car had struck a tree, and a second car with minor damage. [BBC News]