The first most important difference between Hex and Magic the Gathering is that Hex is an entirely digital game. As such it has some special affordances that can only be accomplished digitally:
In Hex a player can put gems into special socketed cards to give them unique abilities abilities.
In Hex the player's character has a special ability he can cast at any point in the game if he or she has gathered enough resources on his or her previous turns.
Finally, in Hex since the game is entirely digital game. The play has the capacity to change cards by equipping the cards items to grant special abilities.
Example of Hex card customization.
On the website for Hex, the game claims to be a combination Massively Multiplayer Online Trading Card Game (MMOTCG). As such it claims, as of writing this webpage the game is still in beta, to have an open world exploration with Player vs Environment (PvE) and Player vs Player (PvP) elements. Player vs Environment means that a player or players can work together to defeat the AI of the game to complete challenges and receive rewards. Another difference between the two game, is that by combining MMO elements with TCG elements, Hex has developed the ability for player's characters to level up and gain bonuses based on their experience in game. These bonus can be personalize so that no two player-characters have to be the same.