Actually, we can found the relativity of words every where in tipitaka.When we recited and memorized pāli, we will see the relativity between words, meaning, sutta, section, nikāya, pitaka, antedate&
predate cannons. This relativity is called "holding together by a thread (suttena susaṅgahitāni)" in nidāna of V.N. Verañjakaṇḍa. And it is what mahāsāvaka did in buddha's time and at 1st saṅgāyana. So, when buddha still alive, he complimented them in A.N. Ekakanipāta, Etadaggavagga. Because they helped him to describe his teaching (in their own schools), and he knew by sabbaññutañāṇa "these professional monks will relatively categorize my teaching to let it going on for 5000 years".
The tipitka professors never explain us this reason, because they recited and memorized pāli, so they never found the serious conflict between the cannons, just the through-reader especially translation version, often make the nonsense doubts.