What is the difference between Sync in background and automatically

[realistdreamer 23]

Thought I knew the difference of these two settings in options, but now unsure.  No documentation that i can find.  Syncing automatically makes sense, but what does syncing in the background add?  Oh yeah, Windows client.

[FreeStyle 0]

It seems this option is responsible for evernote to remain active in the background, with it's statusbar icon.