AMS is a HUGE addon with tons of configuration settings, per category settings, Category Overrides (which means you can overide global AMS options and set different options value like Layout Type for example).
AMS includes a fairly light weight Comments System (very similar to the Comments System in XenForo Media Gallery). This system is controlled by both Permissions as well as being able to be enabled/disabled on a Per Category basis.
AMS includes associated discussion threads (similar to the Associated Threads feature that is included with the XenForo Resource Manager). This is also a per category option.
You can use One, the Other, Both or Neither on a per category basis. This gives Admins several options vs only having one. Some people like comments, some like associated threads, some like to use both and some don't want to use either.
As for Ratings/Reviews. This is controlled by permissions as well as per category enabling/disabling. It also has per category options for Ratings Only, Ratings and Reviews, Reviews only, Pros and Cons, Allow anonymous reviews.
All of these can be full enabled with all the bells and whistles OR they can all be fully disabled.
PS: I wonder whether there's an Admin demo I could play with to find the answers myself?
No, just a frontend demos:
XenAddons Demos (note: these addons of mine are highly configurable, I can't demo everything, so what you see is only about 5% of what the addon can actually do).
If you have a local host environment, you can contact me via Conversation to work something out
