-200ER = extended range
-200ERX = still in experiemental - presumably to become the LR eventually.
-200LR = It may instead stand for longer
Either way the 777-200ER has less range (around 1500nm or 2000nm less, I believe) than the 777-200LR... the new, 'next-generation' 777.
As I say, I assume that the 767-400ERX will become the 767-400LR when it's launched. (This is just an educated guess, however)
All of them, of course, have super spiffy jolly extended range - just some have more than others.
FLY DELTA JETS
and sail UNITED STATES LINES
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