The way voting is done is so different that I strongly suggest viewing Odyssey as an expansion only. Although very useful one because the board is much better.
In the base game, players get six chits numbered 1 through 6 which are used for secret voting.
In Odyssey players are handed a little board with holes where you push a little peg in to indicate what you vote for. For one, this makes scoring a bit of a nuisance because these boards are bigger and can't be put next to the pictures. The other thing is that when you place the boards on the table face down, you can actually still tell what people voted for!