Quant or software engineer?
The honest difference is not difficulty. It is what the code is being judged for.
What transfers, and what does not
Data structures, complexity and clean decomposition transfer entirely. What does not: a trading interview cares about the tail, not the average. Allocation in a hot path, a lock you did not need, an unpredictable branch — these are the parts a general software interview lets pass and a trading one stops on.
The second gap is probability. A developer seat at a trading firm still gets asked to reason about uncertainty, because everyone on the floor has to.
Is the pay difference real?
At the top firms, yes, and it is concentrated: a small number of employers, a small number of cities, and a hiring bar that reflects it. The median across the industry is much closer than the headline numbers suggest.