The tips in tipped bullets are also designed to act like a plunger - the area below them under the copper will have varying amounts of empty space above the lead, depending on a given companys design. When the bullet hits the animal the tip gets smashed back on the copper with nothing underneath supporting it for a short distance. That helps ensure rapid and thorough disruption of the rest of the bullet as it goes through the animal.
Open-tipped match bullets are a bit more hit-or-miss on how consistently they open - the tip isn't as much of a "hollow point" as you find in pistol bullets, as it's usually just a tiny opening in the tip, so they can be a bit more finicky in actually opening up, how much, and how fast. It's not black-and-white, good/not good, but the tipped do work better.