Hi,
Basic difference is the way its getting the data for monitoring. System monitoring is based on CCMS and the new technical monitoring has n number of data providers, most important one would be diagnostic agents. it is more powerful and collects more metrics than CCMS agents.
check out the Data Providers in Technical Monitoring: What, Why and Hows?
refer more details here SysMon FAQ 02 - Technical Operations - SCN Wiki
Thanks
Jansi