It's a lot more than a webview in the sense that keyboard is a first-class citizen, everything is accessible via keyboard, the bindings are much more reliable and responsive, and many more features make it a predictable and stable experience.
For example, qutebrowser supports a hinting mode where I press Enter to activate a link after selecting it with hints, which almost entirely eliminates accidentally clicking the wrong link, something I still do occasionally with Vimium+Firefox.
It is also much more scriptable, so I can for example create a keyboard binding for clipping selected text (with references) directly to my localhost pastebin.
Every action you can imagine is scriptable and bindable.
It has built-in support for adblock and granular JS/image/etc permissions.
Great keyboard-accessible bookmarking system.
Keyboard-accessible and reproducible settings and bindings with autocomplete and lookups.
Not to mention that it does not on a regular basis non-consensually take away features I use/introduce features I don't want and can't disable.