I don't know how purchases from ticket resellers work, but when I made our reservation directly with DC, here is what happened:
I received an email "Order Confirmation" that included a link to our eTickets.
When I click on the eTicket link, the first page is our "Discovery Cove Reservation". It lists our admission type (in our case, Day Resort with Dolphin Swim) our reservation date, the number of people under our reservation, our method of payment, and our confirmation number. This is all we need for our DC day.
The pages that follow are our eTickets for SW & Aquatica. Each of those have a specific individual's name on them (one for each person under our DC reservation). Our DC reservation date is listed on the top of each SW/AQ voucher, but the "legal terms" indicate that this ticket will expire 14 days from the date of first use. These tickets have a scannable bar code, and the tickets must be brought to the gate at SW or Aquatica if used before our DC day (if you visit DC first, then you can use your DC ID card to get in to the other parks).
