FORMAL: elevated, learned, pretentious, ornate, flowery, archaic, scholarly, pedantic, elegant, dignified, impersonal, elaborate, sophisticated, formal, cultured, poetic, abstract, esoteric (hard to understand), colorful, eloquent, euphonious
CASUAL/SLANG: abrupt, terse, laconic, simple, rustic, vulgar, slang, jargon, dialect, simple, colloquial