side projects show you can clone code on github and push it to your own repo. Interviews show you can articulate what you know in a convincing fashion, and that you have done homework on the company as well as your skills of inference and general personal skills to glean into what sort of answer the particular interview is looking for at the time. Something a lot of people really miss out on when bikeshedding over how terrible whiteboard questions are or interview question xyz is
Pass off someone else project as your own? Doubtful. This attitude comes across as having trust issues. To me, it's a sign of a company with a rotten culture to be avoided.
But if someone was able to clone and deploy someone else's project and pass it off as their own, it at least demonstrates that they know git, the command line and some ops.
