There is no universally applicable definition. But in general it's usually understood like this:

• Junior: New in the technology. Can only solve basic problems. Is not yet aware of all the possibilities the technology has to offer. Might require mentoring to achieve their full potential.
• Mid-level: Proficient in the technology. Can solve most problems on their own. Is aware of the existence of most possibilities of the technology, but might not be experienced in using every single one. Can improve their knowledge without requiring a mentor.
• Senior: High level of experience in the technology. If there is a problem they can not find a solution for, it's likely unsolvable. Doesn't just know which possibilities the technology offers, but also has the knowledge to make good decisions when to use which. Can mentor other developers.

There is no universally applicable definition. But in general it's usually understood like this:

• Junior: New in the technology. Can only solve basic problems without assistance. Might not yet be aware of all the possibilities the technology has to offer. Might require mentoring to achieve their full potential.
• Mid-level: Proficient in the technology. Can solve most problems on their own. Is aware of the existence of most possibilities of the technology, but might not be experienced in using every single one. Can improve their knowledge without requiring a mentor.
• Senior: High level of experience in the technology. When they can not find a solution to a problem, then it's very likely unsolvable. Doesn't just know which possibilities the technology offers, but also has the knowledge to make good decisions when to use which. Can mentor other developers.