Mycenaeans are considered Greek.
Minoans generally not considered Greek.
Their script, Linear A, has never been deciphered, so we don’t actually know what language they spoke, but most linguists think it wasn’t Greek, based on how poorly Linear A’s signs map onto Greek phonetics when tested as they do successfully with Mycenaean Linear B.
Culturally the Minoans also look distinct from later Greek civilization. Different religious iconography (bull-leaping, goddess-centric imagery), different art style, no clear warrior-elite hierarchy the way Mycenaean and later Greek society had.