Depends on the phone. Wasn't able to get back to this.
There are several calendars in the calendar app, and they are often color coordinated. For example, my Google Calendar is blue, my School Calendar is green, etc. When you add an event, one of the fields yoy can change at the top is the add to calendar field. Tap that and you have choices for 'My Calendar' and your Google account. If you want to sync, you should choose Google account. The My Calendar bit is ths local calendar put there for people who don't want to sync their info to cloud.