Originally Posted by
MSPeconomist
In the days of paper tickets, revalidation meant the agent making a phone call (IIRC to book the space) and then sticking a one line sticker on the ticket coupon. Reissue meant that an entire new booklet of flight coupons (the ticket itself) was printed and the old ticket was voided.
AFAIK the modern version is that you get a new ticket number when the ticket has been reissued.
Reissue means that the entire ticket (or the remaining coupons) are EXCHANGED and a new ticket is created. This must be done when the routing or fare structure changes. Revalidation can happen when the routing or fare structure does not change.