A cash ticket means you can directly swipe the ticket to enter without queuing to exchange the ticket;
The e-ticket will give you a voucher and you can exchange it at the ticket office.
Of course, it is convenient to pay in cash.
Ocean Park does not allow the bringing of food. There are many restaurants inside, and of course, they are quite expensive. Meal vouchers can be used to exchange money at restaurants, and the price is slightly cheaper after conversion. Because I didn't like the meal tickets for designated restaurants and I wasn't sure what I wanted to eat, so I didn't buy a meal ticket in the end.