I tried to look up something simple like Package Control to determine if its version 2.x or 3.x installed, but even when browsing the Installed Packages folder, the only thing I could find was a created date of the plugin - created date shouldn't be used for version verification.
Checking out the website: https://packagecontrol.io/channel_v3.json it has a version number as part of the package, setting, but how would a Sublime User retrieve this for an installed package?
I don't imagine if there is any major difference between operating systems, but if you know of anything major (not available in one), please list.
In the command palette search for "Package Control: List Package" There you will see v<version number> under the package name.