Legends Untold is much more of an adventure RPG style game. I have One Deck Dungeon and like it. But, they are very different.
One Deck Dungeon has no map, or long term character development (just stat upgrades. ODD is also about dice allocation (kind of like Yahtzee), but gives choices in how you allocate the dice, and what reward you take.
LU gives you choices that drive a story. Dice are used to determine results.
Both very different games. Keep in mind that LU will have multiple packs to expand the story/world to a very large degree. ODD will have extras also, but I suspect not as many as LU.