Managing Storage
I am paying for 200 GB of I Cloud storage and 100 GB of Gmail storage. Is this storing the same things? Why do I need extra storage on both I Cloud and Gmail?
iPhone 13
Google storage is used primarily for Gmail, Google Photos, and Google Drive.
iCloud Storage is used for iPhone and iPad iCloud Backups, iCloud Photos, iCloud Drive, syncing iCloud Contacts, Calendars, Notes, iCloud Messages, etc.
It is impossible to say whether you need both without knowing what it is that you are storing on each. There are a few things that you can move from one cloud service to the other if you are willing to accept different capabilities of the service. Google Photos could be used instead of iCloud Photos in some cases but there are substantial differences between the two.