Here is the list of all the default views and what they mean.
All - This lists all open tickets.
Assigned to me - This lists all open tickets that are "Assigned to me".
Unassigned - This lists all open tickets that are not assigned to any agent.
Assigned - This lists all open tickets that are assigned to some agent.
These notes will be moved to "private notes" when that feature is added to KB. In the meantime, it is posted here.
In Freshdesk "All" means "All open and closed" tickets. When they list only open tickets then they are explicitly about it. For example, they have "My open and pending tickets"
Helpscout lists only "open" tickets by default. For example, their list of "Unassigned" tickets will list only "unassigned" open tickets.
Closed - This lists all closed tickets.
Spam - This lists all tickets that are marked as "Spam".
Trash - This lists all tickets that are marked as "Trash".