Tarot Cards are always in set of 78, if deck has few extra they are duplicast of already existing cards ,but with different image .The names of the cards can slightly change ,but the main idea behind each card is always there .
Oracle Cards can be any number and they can have any sort of theme you can imagine .The number of the cards can vary from 22-30 to 150 in some cases .
I have angel ,fae folk ,celtic ,totem animals ,druid plants themed oracle deck .There are also Gods and Goddesses Oracle Cards .
Oracle Decks come more often with small booklet ,that gives you an idea what is the meaning of each card .Many of them come at least with few spreads ,which you can use in your readings .
Tarot Decks can come with booklets too if it is not exactly standart deck ,or it can come with just the deck in box .
I use them in same way for divination ,but I use different spreads for each and any of them .You can use both of them in spells and for divination .If you have God or Goddesess Oracle Deck you can use the cards to represent a deity on your altar .
I use Oracle Decks for more daily guidence and Tarot for serious dilemmas .