Administrator acccount and domain admin account

Hello,

I have a query about Administrator and domain admin account , 

1)Do administrator account have full access to all the domain controllers in that domain , also what level of access he have on another machines in the domain????

2)Domain admins have full control over all DC's, workstations all the machine , correct me if i am wrong.

Also , let me know if domain administrator group and administrator group are same ,once machine is added to domain.

Paramesh KA