Delusional Insight or Delusional Insight: What's the Difference? If I confused you, don't be alarmed! This article will talk about a slightly different subject. These two phrases differ only in spelling in their origin. Since “insight” is a noun (accordingly, o is a suffix of an indefinite form, and -enium is the ending of the instrumental case), then these words are exactly the same! Just different spellings of the same thing. Therefore, you can safely use the second name (delusional insight) in your speech or writing!