Was is the difference between "uparujjhati" & "nirujjhati"?

In the Pali, nirujjhati (ni + rudh + ya) appears to be a verb for the noun "nirodha". > *nirujjhati* > >*ceases; dissolves; vanishes.* > >*to be broken up, to be dissolved, to be destroyed, to cease, die* Uparujjhati (upa + rudh + ya) appears similar in etymology, however differs in the prefix. > *uparujjhati* > > *stops or ceases* > > *to be stopped, broken, annihilated, destroyed* I have done some examination of the usage of these words in the Pali suttas and, for now, I think their meanings or usages are contextually different. How can these two words be linguistically distinguished?