At the API layer, they are different objects
Perp endpoints use the perp `meta` response and integer asset indices. By contrast, Hyperliquid's official outcome docs say outcome assets are built from an `outcome` id plus a binary `side`, with representations like `#<encoding>`, `+<encoding>`, and `100_000_000 + encoding`.
That is a useful signal for researchers: HIP-4 markets are not just one more perp namespace. They are a separate instrument family with their own identity scheme.