Commonly confused conditions, taught side by side to build differential reasoning.
Students sometimes treat "prefers routine" or "intense focused interest" as automatically diagnostic of ASD on its own, without weighing whether the core social-communication criterion is also met.
Grandiosity during mania (e.g., inflated self-belief while energized and sleepless) is sometimes mistaken for a fixed delusion; context (does it resolve as the mood episode resolves?) matters for telling the two apart.
Students sometimes assume any anxiety with physical symptoms is "basically panic disorder." GAD also produces physical tension symptoms, but they build gradually rather than surging abruptly within minutes.
Students sometimes think "mood swings" (rapid, moment-to-moment shifts) indicate bipolar disorder. Genuine manic/depressive episodes are typically sustained over days to weeks, not minutes to hours.
Students often assume PDD is simply "a milder form of MDD." Severity and duration are separate dimensions: PDD is defined by chronicity, not by being categorically less serious.
Severe, elaborate compulsive rituals can look "bizarre" to an outside observer and be mistaken for disorganized behavior; the presence of a specific anxiety-driven trigger-and-relief structure is the distinguishing feature of OCD.