What separates them
The Perseus is the more specialised paddle. It supplies pace, and it asks you to supply the control, which is a good deal if you already have fast hands and a bad one if your resets are the weak part of your game.
The Hyperion is the paddle you can play every shot with. It gives up some of the Perseus's put away power in exchange for a more forgiving face and more predictable behavior on touch shots.
If you are not sure which of those describes you, that uncertainty is itself the answer, and it points at the Hyperion.
Generations, and why they matter more here than usual
JOOLA has iterated both lines quickly, and the name on the paddle has covered meaningfully different constructions over a short span. A listing that says only Perseus or only Hyperion is telling you less than it appears to.
The dividing line that matters is thermoformed or not. The earlier runs of both are simpler paddles that need no perimeter check and behave more predictably as they age; the later ones are stiffer, more powerful and carry the delamination risk. Neither is worse value, but they are different purchases and should be priced differently.
Read the full title on the listing rather than the model name, and if a generation is not stated, treat the face texture and the tap test as the things you are actually buying on.
Secondhand availability and what it means
The Hyperion turns up used in real volume, because each new generation pushed the previous one out of a lot of bags at once. That is good for price, and it means paying attention to which generation a listing actually is.
The Perseus holds its value better because the players who want one tend to want that specific paddle. Expect a smaller discount and treat it as a signal rather than a problem.
Both need the same perimeter tap test on their thermoformed generations, and both are raw carbon, so face texture is the other half of the valuation on either.