Welcome to Meta Dave! 
The short answer is yes they are the same. Staff are either admins or moderators. They are the same according to Understanding user statuses, roles, and permissions.
To save money you can perhaps look at utilising TL4 (Leader) as they do not count towards this staff limit. Furthermore, you can explore with category group moderators
To compare what privileges TL4, group moderation and staff have refer to the topic below
Hope this helps 