What's the difference between self-managed and SaaS users? To me gitlab is a SaaS ? I mean if I'm self hosting on digitalocean doesn't that just mean that I'm

What's the difference between self-managed and SaaS users? To me gitlab is a SaaS ? I mean if I'm self hosting on digitalocean doesn't that just mean that I'm using your FOSS and doing all the work myself and completely separate from gitlab anyway other than the common codebase? Sorry, I'm not a guru of gitlab and don't know all the common parlance.