Tarot cards are a deck that follows suits (Court, Italian and Baton), elemental (Earth, Fire, Water and Air), numerological, and astrological meanings. When giving a reading with this deck, each card has a specific meaning that you are to follow. Which means you are to memorize each meaning of every card. This is the appropriate way to doing an accurate reading with this type of deck.
Oracle cards are different. There are numerous different types of decks. From romance to healing. They come with guideline books to help you understand what each card signifies. When giving a reading, you connect with your own intuition and Divine guidance. You are on your own with your Higher Self to do a reading. Some find this intimidating. These type of decks also approach in a more positive way, different from the tarot "Swords Suit" and the "Tower" card.