When you create a reoccurring event the system creates each one as an individual event. However, when you make some edits to one, like the main one, or any of the reoccurring events,  these edits will be made to all of the events attached to that one edited. 

Synced Option items include (these will change across the system):
Title,
Description,
Event Coordinator User Information (Username, DisplayName and UserId)
Place
Address
ZipCode
City
State
Country
Latitude
Longitude
Locked
Private

Options that can be edited per events:
Start Date
End Date
RSVP
Comments
Options