I think the skill sets exercised are different.
Background:
So is the more experienced C++ developer going to know more about topics like pointer manipulation and memory management ? Yes.
But by the same token, a really good frontend engineer will know about lots of things I don't know about and for instance you can't do great pattern matching in my head around how to deally design and architect a great Javascript app so it's fast / testable / uses best practices.
Long story short: Both can be very complex in real applications, and it's not a productive conversation to say X engineers or Y engineers are better.
Know what you are good at and what you enjoy and focus if that works for you and go deep there, and don't worry about what someone else is doing.