Aerobic capacity, most will have 10+ years of high mileage training behind them, the higher your capacity, the faster you recover your oxygen debt from a hard effort.
Also the years of training strengthens their form and muscles so even when they pop and fade, their form doesn't deteriorate as much as you see in weekend warriors
Also, in sit and kick races, 1 or 2 seconds per lap is a huge difference to an elite, because they are so fast and highly trained, the gaps between mile pace, 5k pace and 10k become smaller in absolute pace so if an elite runner is running 2 seconds per lap slower than 5k pace(which would be miniscule to a weekend warrior), the elite would be running 10k pace. Some even would only need to slow 1.5 seconds or less than 5k pace to be running 10k pace. Thats only 6 seconds per mile difference between 5 and 10k pace. A difference most hobbyjoggers wouldnt probably even detect but would be comparatively cruising for an elite.