How does the mythology of the Mycenaean culture contrast with that of the later Athenian culture?
The Mycenaean culture preceded the Athenian one and many Mycenaean artifacts are found at archeological dig levels below that of Athens. In fact, some structures identified as Athenian ruins were in fact Mycenaean in origin, such as some walls of early date in the acropolis where Mycenaean shards were also found nearby.
Some Mycenaean deities carry over to Athenian deities, some do not. Mycenaean deitie's statues show them in with their arms in the "epiphany gesture" with both lifted up or with both reaching out to give or receive.
The Mycenaean pantheon included the Furies (Erinyes) and the Winds of later Greek Olympian pantheon. Ares is present in the Mycenaean pantheon under the name Enyalios. Apollo was probably PA-JA-WO ("Paian"). Athenia Potnia is present. Dionysus is prominent as is Poseidon, but his consort Poseida is later dropped from the Olympic pantheon.