AMS is for Article and Article like content.
IMS is an Items database.
IMS is a much larger and much more powerful version of Showcase (which is also an Items Database).
As for similarities, they both implement all of the XenForo Content Type Handlers, so in that aspect, they are similar in that they both have all of the following Content Type Handlers: Activity Summary, Alerts, Approval Queue, Attachments, Bookmarks, Content Vote, Edit History, InlineMod, Moderator Log, NewsFeed, Notifiers, Polls, PreRegAction, Reactions, Reports, Search Index, Searchers, Sitemap, Spam, Stats, Tags, Thread Type, Forum Type, Warning, Widget Definitions.
All of my addons also have Multiple Layout Type (Tile View, Grid View, Article/BlogEntry/Item View, Grid Block Carousel (both simple and full) along with Style Properties that allow you to control which elements display on each of those layout types.
They both implement core systems like Custom Fields, Prefixes, Categories etc.
Both have a rating/review systems. AMS has a very basic rating/review system, where as IMS has the most powerful rating/review system currently (altho, RMS will overtake that again starting with RMS 2.2.12 and or RMS 2.3.0). IMS has replies for Reviews, AMS does not.
Both have a "Series" system
AMS has a light weight comments system that IMS does not have.
IMS has a questions and replies system that AMS does not have.
IMS has an Updates System (similar to XenForo Resource Manager Updates, but much more powerful with features like Custom Update Fields). Updates have a comments system allowing members to reply on updates (XFRM does not have this).
It really boils down to your use case. If your use case is Article and Article like content, then AMS would be my recommendation. If your use case is needing an Items Database, then IMS (or Showcase or RMS) would be my recommendation.
i search the website if there is demo with username and password which i can test both admin and normal user but i couldnt find is it possible ?
I do have IMS installed at my private development site, which is where I provide advanced support for Premium license holders. If you contact me via conversation, I can get you TEMP access so that you can see and use the demo there (frontend only).