"enterprise mobility + security e3" license query.

Hi all

Please can someone help me clear up my confusion. I have 952 of "enterprise mobility + security e3" licenses in my Office 365 tenant and 952 " Office 365 E3" licenses. Majority of my "Office 365 E3" licenses have been assigned to staff members but only a few of the "enterprise mobility + security e3" licenses have been assigned out.

Should I manually assign the "enterprise mobility + security e3" licenses to the staff that have the "Office 365 E3" licenses already? 

I see Azure AD Premium P1 is part of the "enterprise mobility + security e3" licenses.

What does this mean for staff that do not have those licenses to them?

Appreciate any advice.