The differentiation here would be that this guy doesn't have inventory risk (or benefit, for that matter). This guy doesn't own the customer relationship, or the supplier relationship.
It's the difference between owning a pizza restaurant and being the pizza delivery person.
There's different kinds of 'drug dealers'. I've known many 'part-timers' who would buy in bulk and just sell to their friends to make extra cash. Then there's the cops that give drugs away at almost-nothing prices to their friends after they've confiscated them from the dealer who pissed off the club owners he was working with and gave him up. No two dealers are the same...
It's the difference between owning a pizza restaurant and being the pizza delivery person.