Good morning JustJoan R.!
I see that you're having trouble with all calendar events syncing between the iPhone and iPad.
Are all events syncing to iCloud? If so, make sure that you're signed into iCloud on both devices, and that syncing is turned on for iPad and iPhone. You can check this by going to Settings > [your name] > iCloud > and make sure Calendar is toggled on here. You can also check if you sign in to iCloud Home using a browser on a computer to see what is syncing with iCloud.
You may want to also make sure that an account isn't syncing calendar events to your device that may not be on one of the other devices. You can check the accounts on your device by going to Settings > Passwords & Accounts and add any missing accounts using this resource: Add an email account to your iPhone, iPad, or iPod touch - Apple Support
Cheers.