When flying from Las Vegas to Amritsar, 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 Las Vegas Harry Reid Intl Airport to Amritsar Sri Guru Ram Dass Jee Intl Airport flight would often be abbreviated as a LAS to ATQ flight.