ET 574 then UA 2304 at O'Hare
Rome → Chicago → Boston
Timetable, Chicago time
07:40ET 574 from Rome at the gate
15:44UA 2304 to Boston leaves the gate
8 h 04 apart on the timetable
The last days
ET 574 and UA 2304 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.