The insight gained from this work is basic for the design, analysis, and management of fluid systems in space. Actually, the word to use in these instances is understanding . The usage discussed here is in the context of learning more about a process or mechanism from a technical study. Both words describe the ability to mentally grasp what is not readily apparent, to have the power of acute observation and deduction leading to a sight or view of the interior of something. Insight is the fruit of intuition, whereas understanding is the fruit of analysis and observation.
Discernment involves accurately reading character traits or motives or holding art in high esteem.
She discerned that Hillary was not a true friend. The actor's perception of his character's motives enabled him to play the role convincingly. The journalist's penetration led him to conclude that the criminal's icy demeanor hid a frightened young woman. Political acumen guarantees success with a fickle electorate. The judge's discrimination resulted from years of wine tasting.