London Tube and Oyster Card. Travel with ease and confidence. First, know that there is a difference between the Oyster Card and a Visitor Oyster Card. What is the difference? Oyster Card: 5 pound refundable deposit. You can buy them in London. Can top up at any time. Balance under 10 pounds you can get refunded. Visitor Oyster Card: 5 pound non-refundable deposit. You must order it online before you arrive in London and ship it to your home. Not available for purchase in London.…