What would be the best way to compute OOZIE timestamp difference?

I don't know about any library, But you can do it yourself. I am sharing a code that might work.

time_stamp1 = input("Time stamp1")
time_stamp2 = input("Time stamp2")
yrs = int(time_stamp1[:4]) - int(time_stamp2[:4])
mnths = int(time_stamp1[5:7]) - int(time_stamp2[5:7])
days = int(time_stamp1[8:10]) - int(time_stamp1[8:10])
hrs = int(time_stamp1[11:13]) - int(time_stamp2[11:13])
min = int(time_stamp1[14:16]) - int(time_stamp1[14:16])
sec = int(time_stamp1[17:19]) - int(time_stamp1[17:19])
ms = int(time_stamp1[20:23]) - int(time_stamp1[20:23])
print(yrs, mnths, days)
print(hrs, min, sec, ms)

You can use the abs() function if you don't want to know whether timestamp2 is older than timestamp 1 or not or vice versa.

You could use the datetime module.

First, use strptime to convert each of those timestamps into dates. The general format of it is:

from datetime import datetime
date1 = datetime.strptime("2019-07-20T16:34:45.000Z","%Y-%m-%dT%H:%M:%S.%fZ")
date2 = datetime.strptime("2020-08-20T16:20:15.000Z","%Y-%m-%dT%H:%M:%S.%fZ")

(Note: the second argument could be inaccurate, depending on the specifics of OOZIE). For info on how to construct a format/use strptime, see this and this for an introduction to strptime.

Then, you could just do t_diff = date1-date2. This will return a timedelta object, with attributes for years, months, weeks, days, etc... microseconds). It also has a builtin .total_seconds() method. Hope this helped!