Point values of cards
The non-trump suit cards rank in order A-10-K-Q-9-8-7.
The trumps rank the same way with the four jacks on top in the order J♣, J♠, J♥, J♦.
The total face value of all cards is 120 points. The declarer's goal is to take at least 61 points in tricks in order to win that round of the game.
In the grand game, only the four jacks are trumps in the suit order given above for a regular suit game. All other ranks are the same as in the regular suit game (10 is ranked just below the ace). There are thus five "suits" in the grand game (if a jack is led to a trick, the other two players must play jacks too, if they have them).
In a null game there is no trump suit, and in each suit the cards are ranked A-K-Q-J-10-9-8-7.
The goal of a null game is for declarer not to take any tricks. If declarer takes a trick in a null game, he immediately loses and the game is scored right away.