Tramadol is not a "true" opiate because it does not just affect your opiate (mu) receptors, but also serotonin and norepinephrine. For me they feel kind of similar the way I would compare mass amounts of caffeine (being the tramadol) and amphetimines (being true opiods) produce some similar affects without the euphoria. I've had crazy stuff happen on recreational doses of tramadol that I've never had happen on opiates, such as hearing music playing when there was none on. They effect the brain differently so they don't feel the same. Tramadol can also scarily reduce the seizure threshold where opiates don't.