There are so many different numbers for MQ-9 but if you believe this source MQ-9A has 27 hours of endurance and has more internal fuel (1769kg) than Akıncı (24+ hours, ~1600kg)
source:
MQ-9A has an endurance of over 27 hours, speeds of 240 KTAS, can operate up to 50,000 feet, and has a 3,850 pound (1746 kilogram) payload capacity that includes 3,000 pounds (1361 kilograms) of external stores.
www.ga-asi.com
The range figure of 1900 km could be mission radius with some time over target, or it could be with heavier mission loads.
Using single engine (more fuel efficient) and having less drag (probably, less drag area due to single engine mounted on fuselage ) it will consume less fuel for the same range or distance, not specifically but generally of course…
I expect MQ-9A and baseline Akıncı to have similar figures and if Akıncı adds more internal fuel capacity or external fuel it will be same with MQ-9 ER /MQ-9B versions. Once H. Bayraktar told Akıncı has 5000 km mission (ISR) radius, maybe the specs are not current or will be improved with more fuel tanks.