A savage fight is a hard raid boss. An Ultimate is twenty minutes of flawless execution by eight people with no room for a single mistake, and the clear rate across the playerbase is in low single digits. They are on this page together because people shop for them together, but they are different products at very different prices and the cards say which is which.
Nobody searches for "an Ultimate". They want Futures Rewritten, or the Omega Protocol, usually for the weapon and the title. All five are listed separately with their own art so you can click the one you came for instead of hunting inside a dropdown.
Pick a slot in the party instead of handing the character over and you are in the group for the clear, which means nobody signs into your account and the clear credit is genuinely yours. It costs more because carrying a learner is harder than bringing a seventh veteran, and for an Ultimate most people want it that way.