I was going thru 12cR2 documentation, and description for Administration group and Dynamic group looks same to me.
Do any one of you know what's the real difference between them?
Any one of you started using this new feature in 12c?
Administration groups and dynamic groups are similar in that their membership is dynamic, i.e. you specify the membership criteria based on target properties, and Enterprise Manager will automatically add the targets into the appropriate administration group and/or dynamic group(s) if the targets' properties match their criteria.
However, administration groups have additional semantics. As it is mentioned in the doc: "Administration groups greatly simplify the process of setting up targets for management in Enterprise Manager by automating the application of management settings such as monitoring settings or compliance standards. Typically, these settings are manually applied to individual target, or perhaps semi-automatically using custom scripts. However, by defining administration groups, Enterprise Manager uses specific target properties to direct the target to the appropriate administration group and then automatically apply the requisite monitoring and management settings. This level of automation simplifies the target setup process and also enables a datacenter to easily scale as new targets are added to Enterprise Manager for management."
So you use administration groups primarily to automate the process of setting up your targets for monitoring/management. Once a target joins an administration group, then Enterprise Manager automatically applies to the target the monitoring templates and/or compliance standards and/or cloud policies that you have associated with your administration group. Because of this feature, a target can belong to at most one administration group. This is to prevent conflicting scenarios where a target is part of multiple administration groups that have different associated monitoring templates.
Both dynamic groups and administration groups support group operations -- running jobs, reports, etc.
So if you want to leverage the automation of target setup provided by administration groups/template collections... then use administration groups.
If you want to leverage the dynamic membership of groups and have requirements that a target needs to be part of multiple of such groups, use dynamic groups.