Elite Dangerous Horizons and Odyssey Not Compatible

A post to the Frontier Forums from Frontier Community Manager Bruce G explaining that next week's launch of the new Odyssey expansion for Elite Dangerous will divide the community, as only owners of the expansion will be able to play the new Odyssey content (thanks Eurogamer). Odyssey players can also temporarily enter a Horizons mode to allow them to play with Elite Dangerous: Horizons owners (but not with Odyssey players). Here's word:
All Elite Dangerous: Odyssey players will gain access to the new features, including planetary improvements, enhanced lighting, and textures. The differences will mean that Elite Dangerous: Horizons players cannot share a gameplay session with those playing Odyssey. However, Odyssey owners will be able to share a session with and play with those in Horizons by launching the game in Horizons mode – though if they do this, they will temporarily not have access to the new Odyssey features.