What is the difference between primary and contingency nominee?

In the abnormal circumstances where the primary nominee passes away prior to the Account Owner, the remaining portion may be payable proportionately to any surviving primary nominee. In the event that there isn't a surviving primary nominee, the contingent nominee will receive the assets pursuant to the allocation identified. In the event a contingent nominee passes away prior to the Account Owner, then the contingent nominee share will be divided proportionately among the surviving contingent nominees.