Personally (as a dev), I wouldn’t particularly care that you know a specific library (the chance of us using the exact same library is pretty slim and will probably change when the project changes). But I would care to see that you are using a library when it makes sense.

So, if you implemented a hashtable yourself and I spotted that, I’d remember that as you either not knowing that that’s called a “hashtable”, so you didn’t find a library for it. Or I might think that you’re potentially stuck-up, thinking you can do a better job implementing it yourself.

The aspects I’d look for, starting with the most important:

1. Does it seem like you have fun when programming?
   I don’t need you to be writing humorous commit messages, but if it looks like you just specifically coded some portfolio applications three years ago and then never touched them again, that wouldn’t leave a good impression on me.
2. Do your projects fulfill an actual need and look like they’ve seen real-world use?
   Writing out some example applications is a whole different shtick than actually making it work in the real-world.
3. Do you have unit tests? Is your commit log clean? Is your project reasonably documented?
   I can teach technologies and architecture, but it’s much harder to teach a drive for good code quality.