Hello,
You are almost correct. Just a small difference.
SIPC is for private cloud (not every company would have that - it's extremely expensive) and requires vitual appliance to be installed, where as shared insight is for vitualized environment with a virtual server Windows 2003/2008.
Symantec Insight for Private Clouds (SIPC) is a virtual appliance that can be used for SEP 12.1 RU3 and above's Insight/Reputation-related lookups on dark networks (no Internet connectivity). A rough analogy is that SIPC is like a "LiveUpdate Administartor 2.x server for Reputation" (creates an in-house mirror of what is on the Internet servers).
There are substantial system requirments for this virual appliance and SIPC is an optional add-on which must be purchased. It's best suited for very large high-security networks (tens of thousands of endpoints with no Intenet access) in my understanding. Sales should have more info for you, if this sounds like something that would be of interest.
https://www-secure.symantec.com/connect/user/paul-murgatroyd
The Symantec Endpoint Protection Shared Insight Cache eliminates the need to scan files in a virtualized environment that Symantec Endpoint Protection has determined are clean. When Symantec Endpoint Protection scans a file for threats and determines it is clean, the client submits information about the file to Shared Insight Cache. When another client subsequently attempts to scan the same file, the client can query Shared Insight Cache to determine if the file is clean. If the file is clean, the client can bypass virus scanning on that particular file. If the file is not clean, the client scans the file for viruses and submits those results to Shared Insight Cache.
The SIC server works with Symantec Endpoint Protection (SEP) 12.1 clients, especially in virtualized environments, to improve on-demand scan performance. SEP clients can be configured to request information on unknown files and submit information on known files to/from the SIC. The SEP client performs these lookups during all scheduled and on-demand scans. This allows the the client to substitute a small amount of network traffic for a larger amount of disk I/O by not scanning files another SEP client has already scanned and determiend to be safe.
https://support.symantec.com/en_US/article.HOWTO81020.html
Regards,