I just came from an orthodox funeral & noticed that the women were on the right side of the room & the men on the left. By weddings however it's the opposite with men on the right & women on the left. What is the reason for this? I have noticed this at other funerals as well so it wasn't a fluke. I would appreciate a source for this custom.
I never paid attention to this until you mentioned this now.
I think the reason for that funeral arrangement makes sense, having been to a few too many funerals, lately.
Many funeral chapels have two sets of doors. The rows of benches face the front of the room. One enters the chapel from the "lobby", which would be to the right when facing the front of the room. The doors on the opposite side of the room usually lead to the parking lot where the hearse is waiting. These are the doors on the left side of the room when you would be facing the front of the room.
As it is usually the men who escort the hearse, and they would be the ones leaving the chapel first, it makes sense to have them seated closest to these doors on the left side of the room.
I'm unaware of any halacha that dictates any seating arrangement, so what I stated is based on what I have seen in chapels. On rare occasions, have I attended a funeral held in a shul. (Personally, I don't like the idea of doing this.) But, then, again, most Orthodox shuls have the women upstairs or in the back, anyway.