Several US airport immigration queues seem to differentiate between "first-time ESTA visitors" and "returning ESTA visitors" – what exactly is the definition for that distinction? This is my third trip to the US, I have had fingerprints taken before, however all my previous trips to the US were with an older passport and an older ESTA.
(Bonus question: How much faster can the "returning ESTA" line at EWR be expected to be vs. "first-time ESTA"?)