Safari has: (0) Favorites, which can have icons turned off and be text menus with nesting across your browser bar horizontally, (1) Tab Groups, which persist

Safari has: (0) Favorites, which can have icons turned off and be text menus with nesting across your browser bar horizontally, (1) Tab Groups, which persist and live in the side bar vertically with lists under each, and (2) ephemeral tabs (transient, today, etc.) that live above the tab groups, and can disappear when you quit/rerun browser or be restored (I use that mode). And, just for fun, it also has (3) "Pinned Tabs" that stay pinned at the left of your tab row. Both (1) Tab Groups and (2) ephemeral tabs have their own unique (3) Pinned tabs. Certainly favorites are bookmarks while tab groups are tabs, but there's little difference in practical use as you can right click a favorites hierarchy and "open in tab group". The ephemeral class are unique per Apple device, while the Tab Groups are shared across devices. Both are synced across devices, you can browse to the ephemeral class on other Apple devices using the "iCloud Tabs" button at bottom of sidebar.