This glib reply is true but it doesn't cover the other differences, so here is a slightly longer reply ....
Both the Tarot and the Oracle cards are a means of Divination, to look into the life of the querrent. They can help when you are at a crossroads and need some guidance. The cards can NOT tell you what is going to happen and if anyone tells you they can ABSOLUTELY guarantee an outcome - keep your money and run in the opposite direction (but I believe that was a previous blog).
The traditional Tarot is a deck of 78 cards - from around the 15th Century - the deck is divided into 4 suits Cups, Wands, Swords and Pentacles (or Coins) - the 'pip or Minor Arcana' cards start at Aces and like a normal pack of cards end at Kings.
The Oracle differs in that there are less cards and they are not split into 'suits' nor do they have Major Arcana and they are often based on a 'theme' for example - I have the Wisdom of Avalon, Earth Magic, Angel Therapy ..... to name a few!!
Both the Tarot and the Oracle cards are used the same way, you can use the same spreads (my personal favourite of Past, Present, Future)!
Well............ now you know why I give the shorter answer when asked!!
love and bright blessings to all
Lesley x x x