When flying from Greensboro to Bologna, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Greensboro/H. Point Airport to Bologna Guglielmo Marconi Airport flight would often be abbreviated as a GSO to BLQ flight.