If you use the same Apple ID on both and use iCloud then what you do on one device it will want to do on the other one too. You can, of course, delete apps and just not download them on the other device. Those aren't using iCloud as such.
Configure iCloud settings on the devices to decide what to sync:
Change your iCloud feature settings [iOS and Mac] - https://support.apple.com/HT207689 - "'When you turn off an iCloud feature on a device, information stored only in iCloud for that feature is no longer available on the device. If you turn off Mail, Contacts, Calendars, Notes, Reminders, or iCloud Photos on just one device, you can still view and change your information on iCloud.com and on another device you set up for that feature."