Hmm, okay well I'm studying for the MCAT as well, and this is kind of how I've been differentiating them:
Schizoid & Schizotypal are 2 of the 3 personality disorders belonging to Cluster A (A for pAranoid), but not defined as Schizophrenic disorder.
Schizoid personality disorder: these individuals are avoidant, introspective lifestyles, unemotional, deeply detached from others.
Schizotypal personality disorder: These people have hallucinations, eccentric thoughts and behaviors and magical thoughts. High likelihood to develop into Schizophrenia.
Schizophrenic Disorder:
Paranoid: auditory hallucinations, grandeur delusions.
Disorganized: Disorganized thoughts/behaviors, no hallucinations/delusions.
Catatonic: catatonia.
Undifferentiated: No predominant symptoms.
Not really a quick way to memorize them. I haven't found any mnemonic or anything, but I think it's pretty easy to differentiate between them. While Schizophrenia and the personality disorders may share some positive and negative symptoms, Schizophrenia is characterized by a loss of control, or that their thoughts are being controlled by an outside force.