Onboard credit is money applied to your account for use during the sailing: drinks, excursions, the spa, specialty dining.
It is the most common remedy for a price drop claim, particularly after final payment. The constraints matter. It is almost always non-refundable, it cannot usually be used in the casino, and anything unspent when the cruise ends is lost rather than returned.
That makes a credit payout worth less than the same amount in cash unless you were going to spend it anyway. See onboard credit or a refund.
