Why are there so many different types of tarot card decks?

There are numerous types of tarot card decks for a psychic to use during psychic readings.  However, all of the tarot card decks have the same basic layout of cards.  Depending on the type of tarot card deck, there may be different names for The Major Arcanas, but they usually do follow the same type of format.  The Major Arcanas are Cups, Wands, Pentacles and Swords.  From one deck to another, there may be different artwork and/or slight differences of meaning for the particular card.  A psychic reader's cards are very valuable to their readings.  They help communicate the message the reader wants to give to the client.  Tarot cards can help the reader decipher the past, the present and the future of a particular question or situation.  A psychic reader will pick out a tarot deck by what he or she feels most drawn to and feels spiritually connected.  

There are tarot cards and Angel/Oracle cards.  Tarot cards are used for overall readings and futuristic readings.  Angel/Oracle cards are used to help communicate with a higher power and to help a psychic medium channel.