Sort of. Those with ptsd can have a variety of symptoms, e.g., flashbacks of the trauma, hyperalertness, or overreaction to casual statements that can look quite like psychosis. Usually, though these are transient and related directly to the trauma. Effective treatment of the ptsd typically makes the symptoms go away.
Psychosis. Ocd patients, as opposed to psychotics, retain insight into their illness, their symptoms are short-lasting, and their behavior is not disorganized.
PTSD. Ptsd can be mistaken for many different conditions, including psychosis, personality d/o (often borderline), bipolar d/o, and others. Usually it does not have the lifetime trajectory that longstanding psychoses like schizophrenia & schizoaffective d/o do, though. Someone with ptsd can become very paranoid and may well be transiently psychotic -- sleep deprivation can lead to this also.