How is a project different from a hands-on challenge?
I'm moving the first steps with Salesforce and I cannot find the "Hands-On Challenge" for the trailhead playground that the Getting Started with the Platform tutorial refers to.
I've already created a developer profile.
The answer to your question - How is a project different from a hands on challenge is - In order to access the hands-on challenges, you must be logged in to Salesforce Trailheads with the username you are using to complete them (usually related to a developer org). You can then access the hands-on challenges at the end of different modules. (not all of them have hands-on challenges)