Those are some complex questions. I don’t think you can nail down either of those concepts “exactly.” They mean different things to different people.
Commonly, Baphomet is seen as one or more of the following – an embodiment of alchemical principles, the dualistic nature of the universe, Satan, a symbol of the biosphere, a/the horned god.
Cernnunos is a Celtic deity about which little is known, but who has been adopted by witches and occultists as a general horned god, or the Horned God.
Pan shares many of these aspects as well.
I don’t know how far along you are in your own occult studies, and I don’t mean to talk down to anyone. I have personally found that the more you learn, the more you see that the most interesting occult symbols have myriad meanings and can both be one thing and another at the same time.
I highly recommend, The Book of Baphomet, by Julian Vayne and Nicki Wyrd.
I think the best thing you can do is speak with these entities yourself and see what they say.
