Just to add some context, on macOS you can look at the seat-belt policy as a rough analog of for basic sandboxing guarantees, where the fewer exceptions you have the stronger your sandbox is. From that perspective, Chrome's policy has around 1/10th the exceptions of Safari.
And of course, that's before we get into more complex forms of isolation that Chrome implements, such as the sandboxed GPU process, or ongoing work into things like network sandboxing, the macOS bootstrap sandbox, and site isolation (origin-bound renderer sandboxing).
* Safari SB policy: https://trac.webkit.org/browser/webkit/trunk/Source/WebKit2/...
* Chrome SB policy: https://cs.chromium.org/chromium/src/content/renderer/render...
And of course, that's before we get into more complex forms of isolation that Chrome implements, such as the sandboxed GPU process, or ongoing work into things like network sandboxing, the macOS bootstrap sandbox, and site isolation (origin-bound renderer sandboxing).