Administrator Clarification

Hi Everyone,

I would like know what are basis or scenario when the Project assigned Admins? some of our Team Projects assigned 2 Admins and some are just 1?

1 Admin https://d.pr/draw/N6gYyt/
2 Admins Screen Shot 2020-06-12 at 07.14.54.png - Droplr

Is it automatically assigned? How?

Thanks Everyone!