There are multiple types of implementations in AAM. Permutations and combinations can go more than 10 types of implementations. Which one to choose depends upon what kind of data you want to collect, which Analytics tool you already have, whether you will be using page level variables or not, and whether you want to implement ID sync or not.
But one should be implementing only with one type, since implementing AAM on a single site or app with multiple types can lead to multiple calls that results in excessive data being shown.
Broadly there are two types of implementations : Client Side implementation and Server Side implementation.
With Client Side implementation data will be collected from your webpage or app, that means signals from a page (key-value pairs) will hit AAM data collection server.
For Client Side implementation, we need DIL code (data integration library), Get the latest DIL library by contacting Audience Manager Help.
If you are using Dynamic Tag Manager (Adobe DTM), then you don't need DIL, just add the AAM tool in your DTM property, and DIL can be later on upgraded to latest version with few clicks if you are using DTM.
Again Client Side implementation has two types : Client side with no Adobe Analytics and Client Side with Adobe Analytics.
With Server Side Forwarding implementation signals will not go from your page or app directly to AAM data collection servers, but they will be collected from Adobe Analytics on server to server basis. That means if you have AAM and AA both, you will have one lesser call on your page.
For Server Side implementation, there are some prerequisites :
Analytics: AppMeasurement 1.5 or later (H code not supported for server-side forwarding)
Visitor ID Service (Marketing Cloud ID Service): Version 1.5 or later
The Profiles & Audiences core service should be provisioned.
Contact AAM Client Care or your Account Manager to enable Server Side Forwarding for your account Audience Manager Help. You also need to add Audience Management Module in your AA appmeasurement.js or AA tool in DTM property, check this help article on Server Side Forwarding.