Role
System AdminSubsystem AdminTenant Admin
How role is given

From the user's profile page/edit modeFrom the Subsystem Setting page -- > General From the Tenant Setting page -- > General
Who can assign the role
System Admins
System Admins, Current Subsystem Admins
System Admins, Current Tenant Admins
ScopeManage all subsystems and tenantsManage only the subsystem he/she is assigned to
Manage only the tenant he/she is assigned to
Create/Manage Campaigns
In all subsystems and tenants

Only campaigns of the subsystems he/she is assigned to
Only campaigns of the tenant he/she is assigned to
Create/Mange News
In all tenantsNAOnly news of the subsystem he/she is assigned to
Add/Edit Users
In all tenantsNA
Only users of the subsystem he/she is assigned to

Edit Subsystem setting (workflow, role, submission form, reports homepage, etc)In all subsystemsOnly the subsystem he/she is assigned to
NA
Edit Tenant setting (tenant welcome strip, tenant categories, etc)
In all tenantsNA
Manage only the tenant he/she is assigned to
Edit System setting (GDPR, Profile fields, Features Global Setting etc.)YesNANA

To know more about other differences, read the attached PDF