The Discount (or Promotional) Code gives you the right to a reduction on the chosen fee (where applicable).

The Activation Code gives access to special fees, reserved and not usable except through its insertion. 

It is issued directly by the organizer of the event or by the competition secretariat of the same.

They must be entered in the fee selection phase, here:

On the contrary, the Voucher must be entered during the payment phase, here: