Two options when installing AM extension to CCM in v7+

Hello,

So with the new version comes the change of implementing AM capabilities into CCM and installing it as an extension.
During the installation using IBM IM at the part related to AM you are asked a question which mode of CCM you want to install... either Model Management or Model and Code Management.

If I understand this correctly if you choose first option you are installing CCM application with only features enabled for AM extension and choosing second option also enables you full CCM functionality ?

Is there any guide/post describing the features and differences of those two modes?

At 1 customer We installed CCM on one server and CCM+AM to second server. They complained about why do They have two instances of EWM installed... it is confusing.
So We said OK as you have no data yet in there We will scratch the CCM (without AM extension) to stop the confusion. But later I have thought if the CCM+AM instance was installed in the second mode (Model and Code Management) and if not - does it mean they are now lacking CCM functionalities?
Can anyone elaborate please? 

Thank you.