Schizophrenia is gradual (or sudden) disorganization of thoughts. Hearing/seeing things happens, but you don't reflect on it like OCD. Schizophrenia is your brain lacking "breaks". When a wrong thought pops in, it will go unnoticed. Like reality-checking.

OCD is almost the complete opposite of that. You constantly, ceaselessly reflect on every thought. OCD is the parking brake being jammed. When even "normal" thoughts pop in, the brain will distort it. It's neurosis VS psychosis.

For me, OCD is always present, even now. My schizophrenia is gone now because of medication. Before medication, my thoughts were very distorted, and I never thought about it. I actually thought it was my environment.