Outlook 365 calendar - save do not send

my colleague is able to add or make changes to an existing calendar invite and save without sending an update to the invitees.  I have permissions to this person's calendar.  When i try to do this i do not have the option to save unless i send an update to the invitees. 

I was wondering why this person can and I cannot?   also, when doing this, do the invitees see the changes made to the invite they received?  i.e. you add a document to the invite but don't want to bother the invitees with an update.  will they see the document added when they open their invite?

thanks.