Hello Mkettler,
It sounds like you have calendar events that are not syncing correctly between the iPad and the iPhone. I recommend starting by checking what the default calendar is set to on the device that has events the other does not, to see if perhaps the events you have been adding are going to a local calendar rather than the iCloud calendar:
Several settings in Settings > Mail, Contacts, Calendars affect Calendar and your calendar accounts.
Default calendar for new events
From: Calendar settings
http://help.apple.com/iphone/7/#/iph3d11102c
If it is set to an iCloud calendar then I would next check to see that the events in question are in iCloud at http://www.icloud.com. If so, try the troubleshooting from the following article on the device that does not have the events. If not, then do the troubleshooting on the device that does have the events.
iCloud: Troubleshooting iCloud Calendar
http://support.apple.com/kb/ts3999
Thank you for using Apple Support Communities.
All the very best,
Sterling