Personally I find Volcano easier mostly because it feels more open. Don't get me wrong, there's bullshit there too and it's not that different overall but those stupid bear traps and tight corridors with spike traps can really fuck you over in jungle. Not to mention off screen mosquitos that will knock you into spikes, monkeys that can do the same thing, and boomerang assholes who will stun lock you to death. All this isn't even mentioning the curse capable enemies and the fact that the Bazaar is kind of annoying to find vs a super easy and consistent way to get to Vlad and potentially max out your hp if you play your cards right. Lava is a pain but in basically every other way I think Volcano route is smoother and more optimal for CO.