[Python] Asyncio order of execution vs trio order of execution

I executed the same code with asyncio and trio more than ones. The order of execution for asyncio seemed to be preserved on every run but not with Trio. Any particular reason that this happens?

asyncio code


async def greet():
print("Greet: Hello")
await asyncio.sleep(1)
print("Greet: World")

async def countdown():
print("Countdown: 3")
await greet()#sleep(0.5)
print("Countdown: 2")
await asyncio.sleep(0.5)
print("Countdown: 1")

async def main():
# Run both coroutines concurrently
await asyncio.gather(greet(), countdown())

asyncio.run(main())


execution result over many runs is same:


Greet: Hello
Countdown: 3
Greet: Hello
Greet: World
Greet: World
Countdown: 2
Countdown: 1

Trio code


import trio

async def greet():
print("Greet: Hello")
await trio.sleep(1)
print("Greet: World")

async def countdown():
print("Countdown: 3")
await greet()
print("Countdown: 2")
await trio.sleep(0.5)
print("Countdown: 1")

async def main():
async with trio.open_nursery() as nursery:
nursery.start_soon(greet)
nursery.start_soon(countdown)

trio.run(main)

Execution order changes with runs


Countdown: 3
Greet: Hello
Greet: Hello
Greet: World
Countdown: 2
Greet: World
Countdown: 1

I want understand why this difference. Does this mean trio really does not care what order it executes the coroutines and asyncio does?

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