You start from scratch, you can pick something you're interested in building and maybe also feel you can succeed at. You make up your own requirements, as you see please, so things aren't ambiguous or changing in requirements constantly.
There's no prior legacy constraints, there's no time constraints, it doesn't require finding ways to deliver faster by leveraging other developers.
You get to spend as much time as you need, go watch tutorials, take a hiatus, come back to it when refreshed, fail multiple times and try again, etc.
You can choose the programming language, framework, library ecosystem, that you're more familiar with and comfortable with.
And so on.
So having someone that can show some cool personal projects I've found isn't always a great way to know if they'll be good in a work environment and on a team.