I think the direct answer to your question is that both have the same access to Apple Events to automate apps and the macOS. So, in that sense, they are equals.
However, due to the native syntax and built-in functions, they are NOT the same.
IMO, JXA has the clear advantage.
JXA is also much easier to learn than AppleScript, in spite of Apple's claim that AppleScript's "English-like terminology" makes it easy to learn.
So, for those that don't have much experience with either, I recommend JXA.
For a more detailed discussion, please see: