The difference between Country and Realm

Country as a noun (chiefly British):

An area of land; a district, region.

Country as a noun:

A set region of land having particular human occupation or agreed limits, especially inhabited by members of the same race, language speakers etc., or associated with a given person, occupation, species etc.

Country as a noun:

The territory of a nation, especially an independent nation state or formerly independent nation; a political entity asserting ultimate authority over a geographical area.

Country as a noun (usually preceded by “the”):

A rural area, as opposed to a town or city; the countryside.

Country as a noun:

Country as a noun (mining):

The rock through which a vein runs.

Country as a noun (vulgar, countable):

The female genitalia, especially the vagina.

Country as an adjective:

From or in the countryside or connected with it.

Country as an adjective:

Of or connected to country music.

Realm as a noun:

An abstract sphere of influence, real or imagined.

Realm as a noun:

The domain of a certain abstraction.

Realm as a noun (computing):

A scope of operation in networking or security.

Realm as a noun (formal, or, legal):

A territory or state, as ruled by a specific power, especially by a king.

Realm as a noun (fantasy, RPG):

An otherworldly dimension or domain — magical, ethereal, or otherwise — usually in reference to one ruled or created by a mystical character.