content-wise, are there any differences from default HTML version if I am going to use Angular version? For example Datatables plugin seem to be missing on Angular. Are the plugins and content differences only matter of demo preview or whole version?
The Angular versions will be the same in the demo and download package.
The SPA versions(Angular, React, Vue) comes with limited but important features and it does not mean to fully porting all the HTML features since the volume of work is huge and most of the HTML features are built with jquery based plugins. However, all HTML/CSS only features are fully available in the SPA versions so you can reuse the templates/components makeup without any issue.