I can't offer specifics, but the way I typically evaluate jr. vs. sr. is whether the person can understand things at the conceptual level or not. Do they understand the design / architecture / reasons why things are/were done in a particular way, do they understand the benefits and downsides, and do they have knowledge about alternatives.

Junior developers almost always only know about concrete things they worked on previously. They typically have a hard time talking about anything other than implementation details.