It is not actually much of a difference;
 $ cat t.py
def func(
    arg: typing.Callable[
        [int, str],
        str # test
    ]
):
    pass

import typing
print("Annotations: ", func.__annotations__)
print("get_type_hints: ", typing.get_type_hints(func))
$ ./python t.py
Annotations:  {'arg': 'typing.Callable[[int,str],str]'}
get_type_hints:  {'arg': typing.Callable[[int, str], str]}

$ ./python
>>> foo: (List[List[List[int, str, bytes]], List[(int, str)]])
>>> __annotations__
{'foo': 'List[List[List[int,str,bytes]],List[(int,str)]]'}