[PragmaticPulp]

This is a good distinction.

Side projects = Fun project that demonstrates skills

Side business = Ongoing obligation that could distract from your job.

Be careful in how you present them.

[ergocoder]

Side project isn't really impressive though like a to-do app in Rust. Yeah, that doesn't mean anything.

Side business actually is. Because it means you can build, launch, acquire, and retain; and you have to deal with customers.

This means you do have skills to be in a senior position.