Both are correct. I looked up the cheapest LAX-PEW fare and these were the change fees:
CHARGE USD 400.00 FOR REISSUE.
CHARGE USD 200.00 FOR REVALIDATION.
NOTE - TEXT BELOW NOT VALIDATED FOR AUTOPRICING.
USD200 APPLIES IN CASE OF DATE CHANGE INCLUDING
REVALIDATION OF INTERLINE SECTORS IF ANY.
USD400 APPLIES IN CASE OF REROUTE OF ITINERARY
AND CHANGE IN FARE OR APPLICABLE RBD.
NOTE- FOR REROUTE PLEASE CONTACT YOUR LOCAL EK
Basically, if your original class is available, the change fee should be US $ 200 with no fare difference as long as the original fare is still there.
If there is a fare difference, the penalty would be $400 PLUS fare difference as you are changing the RBD.