WMI Data Reader Task vs WMI Event Watcher Task

I was reading about WMI

https://msdn.microsoft.com/en-us/library/ms141130%28v=sql.110%29.aspx

vs https://msdn.microsoft.com/en-us/library/ms141744%28v=sql.110%29.aspx

From the articles, it seems like I would use WMI Data Reader ("Obtain information about the presence,state, or properties of hardware components") if I want to query services (for example MSSQLSERVER or SQLSERVERAGENT).

Has anyone set up anything of that sort before? Or found a good example?

Thanks

Ami