Iglishmek vs artlang

Iglishmek and artlang both are nouns.

Word	Noun	Adjective	Verb	Adverb
Iglishmek	Yes	No	No	No
artlang	Yes	No	No	No

As nouns, artlang is a hypernym of Iglishmek; that is, artlang is a word with a broader meaning than Iglishmek:

Iglishmek: a constructed language devised by J. R. R. Tolkien, a sign language used by the Dwarves of Middle-Earth.
artlang: a constructed language designed for aesthetic pleasure.

Other hypernyms of Iglishmek include artistic language.

Iglishmek (noun)	artlang (noun)
a constructed language devised by J. R. R. Tolkien, a sign language used by the Dwarves of Middle-Earth.	a constructed language designed for aesthetic pleasure.