>>11366586There is one thing, it does to receptor.
Another thing is reuptake and transport thing.
While SSRI are "selective(marketing word) reuptake inhibitors" which means, that receptor they act on, they inhibit reuptake, therefore you're left over with less serotonin being reuptaken.
In contrast stuff like dmt acts directly on the place where serotonin is, of course it releases another serotonin by chain reaction, but it acts directly....
TL;DR antidepressants have indereect action while drugs have direct:
Source: wiki/serotonin receptor