interpreting the fractional portion of time.clock() vs time.time(0 measurements

[Peter Hansen]

john peter wrote:
> let's say i'm taking timing measurements in Windows XP
>  
> t1 = time.clock()
> ...
> t2 = time.clock()
>  
> t3 = t2 - t1 = say, 0.018
> what is the unit of measurement for t3? is it correct to say that t3 = 
> 18 milliseconds?
> microsends?
>  
> what if the timing function used for t1 and t2 was time.time()? is it 
> still correct to say
> that t3 = 18 milliseconds? i kinda know that in Windows, time.clock() 
> has higher
> resolution than time.time(), and all i need is millisecond resolution. 
> which of these
> functions would be easier to translate into millisecond units of 
> measurement?

This looks like a repost of a previous question, to which I already 
posted an answer.