Tab management in vivaldi browser

Multiple Windows

The classic way to group tabs. Before stacks became a common browser feature, windows were used with collections of tabs related to a certain task. If your OS or desktop environment provides good window management controls this can still work well.
However window opening and closing will be slower than things like stacks or workspaces.

Tab stacks

The best overview of all the tabs from a single tab bar.
They are low effort, easy, can be quickly made and destroyed.
You do not need to think about what they are called or have a clear idea of what the group you are making.
You can name them if you like, but it is not required

Workspaces

A bit more effort to make than stacks but makes tabs more permanent.
They also provide a far cleaner, focussed look to your tab bar than lots of stacks.
You view one workspace at a time and will not be distracted with tabs that are unrelated to your current activity
you can also have stacks within workspaces if you want the best of both worlds
Benefits over using Windows : are faster to switch between, and are easier to distinguish because you setup unique names and icons.

Sessions

Sessions store collections of tabs with their current state.
To update them or create new sessions you need to save them again.
They serve as a form of backup, to return back to the point in time when you saved them, retaining things like your per tab browsing history,etc.
While you can use sessions much like you might use the other grouping features, it requires more effort.
{ ? also transfer state from one device to another by importing its sessions ? }

Profiles

if you want complete separation, or just want to test the browser in a clean state, and simular
almost like a complete, extra copy of the browser. They can have distinct themes, different keyboard shortcuts, commands and other settings. Your cookies and site data will also be separate between profiles. Thus you can log into one site in one profile and the same site again in a different profile, using a completely different user name. You can also make use of unique windows, workspaces, stacks and sessions under each of your profiles. This ability is both profiles’ biggest strength and their biggest weakness because they have the least integration with everything else.

They are the most effort to setup, since you need to configure all your common settings again, reinstall extensions, login to sites, etc. for each new profile.
There is no easy way to move windows, tabs, stacks or workspaces between your profiles.
You cannot access your sessions from the other profiles. Finally because they are like a full copy of the browser they are the slowest to start.