Archaic vs. Arcane — What's the Difference?

Also Archaic Relating to, being, or characteristic of a much earlier, often more primitive period, especially one that develops into a classical stage of civilization

Known or understood by only a few

No longer current or applicable; antiquated

Understood by only a few.

Relating to, being, or characteristic of words and language that were once in regular use but are now relatively rare and suggestive of an earlier style or period.

(by extension) Obscure, mysterious.

Relating to or being an early or premodern evolutionary form of an organism or group of organisms

Requiring secret or mysterious knowledge to understand.

Relating to or being an early form of Homo sapiens or a closely related species, such as Neanderthal, that is anatomically distinct from modern humans.

Extremely old (e.g. interpretation or knowledge), and possibly irrelevant.

Archaic Relating to a Native American culture prevalent throughout much of North America from about 8000 BC to about 1000 BC, characterized especially by the development of Mesolithic tools and by the increased reliance on smaller game animals as the large Pleistocene mammals became extinct.

Hidden; secret.

A member of an archaic population of Homo.

Requiring secret or mysterious knowledge;

A general term for the prehistoric period intermediate between the earliest period (‘[http://en.wikipedia.org/wiki/Paleo-Indian Paleo-Indian]’, ‘Paleo-American’, ‘American‐paleolithic’, &c.) of human presence in the Western Hemisphere, and the most recent prehistoric period (‘Woodland’, etc.).

(paleoanthropology) (A member of) an archaic variety of Homo sapiens.

Of or characterized by antiquity; old-fashioned, quaint, antiquated.

(of words) No longer in ordinary use, though still used occasionally to give a sense of antiquity and are still likely to be understood by well-educated speakers and are found in historical texts.

(archaeology) Belonging to the archaic period

Of or characterized by antiquity or archaism; antiquated; obsolescent.

So extremely old as seeming to belong to an earlier period;

Little evolved from or characteristic of an earlier ancestral type;