In [1]:

import datetime

In [2]:

today = datetime.date.today()
today

Out[2]:

datetime.date(2020, 10, 28)

In [3]:

now = datetime.datetime.now()
now

Out[3]:

datetime.datetime(2020, 10, 28, 9, 55, 31, 64038)

In [4]:

sorted([now, today])

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-97aef87903c9> in <module>
----> 1 sorted([now, today])

TypeError: can't compare datetime.datetime to datetime.date

In [5]:

def dates_before_datetimes(dt):
    if isinstance(dt, datetime.datetime):
        return (dt.date(), dt)  # return a length-2 tuple with date as the first item, datetime as the second        
    elif isinstance(dt, datetime.date):
        return (dt,)  # return a length-1 tuple with date object
        

In [7]:

dates_before_datetimes(today)

Out[7]:

(datetime.date(2020, 10, 28),)

In [8]:

dates_before_datetimes(now)

Out[8]:

(datetime.date(2020, 10, 28),
 datetime.datetime(2020, 10, 28, 9, 55, 31, 64038))

In [6]:

sorted([now, today], key=dates_before_datetimes)

Out[6]:

[datetime.date(2020, 10, 28),
 datetime.datetime(2020, 10, 28, 9, 55, 31, 64038)]