As stated by other users, games designed for Xbox One only work on Xbox one, while new gold games designed for Xbox 360 will work on Xbox one as of some time last year.
All new Xbox 360 releases for 'games for gold' would be guaranteed to work with Xbox One, so be sure to click the download link on the Xbox One games as well, as you are not only entitled to the games released for your console, but all the free offerings for that month. If you fail to click that download button, you will miss out on it.
Alternativley, if you decide to get an Xbox One in the future, you will immediately have a library of games to play from previous redeemed 'games for gold' Xbox One titles. Of course, you will have to look at your games list online to remind you of all the games, and go online to actually download the content for the Xbox One when you get it.
But if your question is if you get a game that is released on gold that is designed for xbox one but also has a title which is the same substantial game for xbox one on the 360 as is this month with goat simulator you do not get the 360 version of goat simulator just because you have the xbox one version.