Upvote:1
A passenger being on-hold, doesn’t have a clear meaning, it could be the passenger is held at security for investigations or at the gate for border control.
A passenger on standby:
On most modern airlines, flying standby occurs when a passenger travels on a flight without a prior reservation for that specific flight. ... They will then attempt to travel standby on the earlier flight, and failing that, proceed to take their booked flight. This is referred to in the industry as "go-show".
(Source)
Note: Most airlines don’t allow this anymore unless for employees.
Upvote:1
“On hold” means the airline is holding the reservation for you for whatever reason (Usually waiting payment confirmation, but could also be a change in flights).
“Standby” occurs when a passenger travels on a flight without a prior reservation for that specific flight. For example: