Thanks for the answers Dmytro and Rohana.
How about the difference between passati, vipassati, and the 4 "nupassi" in sammaasati?
Looking up in the dictionary vipassati has an additional element "has intuition" according to CPED, besides just seeing.
Thanissaro defines nupassi in sammaasati as "focused" I believe.
example: " There is the case where a monk remains focused on the body in & of itself"
idha, bhikkhave, bhikkhu kāye kāyānupassī viharati ātāpī sampajāno satimā, vineyya loke abhijjhādomanassaṃ;
are passati, vipassati, nupassi essentially equivalent, or are there shades of nuance or difference in meaning on context?