Assets as a cloud service is a complete Digital Asset Management system with extensive metadata management capabilities (folder and asset level), adding custom metadata , custom search filters , along with asset processing capabilities which are offloaded now on asset microservices architecture . We can additionally do custom post processing on updates/ post ingestion like custom watermark by integrating with APP builder on Adobe IO etc , adding custom metadata properties on certain even/logic via custom workflow /servlet or integrating with 3rd pary webservices/API , basic DRM.
You can leverage Asset HTTP API too and it supports content fragment .
It's always current/updated , running and scalable.Asset reporting / insights capability.Connected assets etc. Integration with Brand portal or asset share commons for sharing distribution/collaboration.
dynamic media offers performance improvements by smart imaging concept , storage benefits by creating renditions on fly , dynamic interaction features / multiple image/video presets/viewers which are missing in AEM alone. When using AEM alone without DM , you have to store each and every rendition for assets and cannot optimize image/video delivery based on channel/network bandwidth etc.
in summary - DM can be used for Dynamic Asset rendition creation and delivery. So if your use case is just to generate image and its renditions on fly and use them - you can just use DM
Hence usually AEM Assets with DM as an add on is a powerful combination.
