What is the difference between @types.coroutine and @asyncio.coroutine decorators?

The difference is if you have a yield statement or not. Here's the code:

from types import coroutine as t_coroutine
from asyncio import coroutine as a_coroutine, ensure_future, sleep, get_event_loop


@a_coroutine
def a_sleep():
    print("doing something in async")
    yield 1


@t_coroutine
def t_sleep():
    print("doing something in types")
    yield 1


async def start():
    sleep_a = a_sleep()
    sleep_t = t_sleep()
    print("Going down!")


loop = get_event_loop()
loop.run_until_complete(start())

In this example everything seem same - here's the debugging info from pycharm (we're standing on the "Going down!" line). Nothing is printed in console yet, so the functions didn't start yet.

But if we remove the yield, the types version will start function instantly!

from types import coroutine as t_coroutine
from asyncio import coroutine as a_coroutine, ensure_future, sleep, get_event_loop


@a_coroutine
def a_sleep():
    print("doing something in async")


@t_coroutine
def t_sleep():
    print("doing something in types")


async def start():
    sleep_a = a_sleep()
    sleep_t = t_sleep()
    print("Going down!")


loop = get_event_loop()
loop.run_until_complete(start())

Now we have doing something in types in console printed. And here's the debug info:

As you can see it starts right after call, if there is no result and returns None.

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As for usage, you should use asyncio version always. If you need to run it like fire and forget (running instantly and getting results later) - use ensure_future function.