Differences between removing and deleting in iCloud

Welcome, Mariansapple!

Thanks for reaching out in Apple Support Communities! From your post, it sounds like you're looking for guidance regarding iCloud data. We'd like to see how we can help so you have a better understanding.

When you select to remove from reading now, this simply removes the item you're currently reading/listening to from the Reading Now page. You can learn more on how this works by checking out the link below:

Read books in the Books app on iPhone - Apple Support

If you choose to remove a download, this typically will just remove a downloaded item from your device, but doesn't remove it from any other device since the download is saved locally to the device in use.

Delete everywhere and delete from iCloud will usually remove the selected content from devices that use iCloud with the same Apple ID and will also remove the data from iCloud as well. We think you'd benefit by looking over the resources below as it goes into more details with how iCloud works. Be sure to utilize the "Search this guide" feature at the top of the first resource since this will give you additional info on more specific features you might be interested in.

iCloud User Guide - Apple Support

Manage your iCloud storage - Apple Support

Best wishes!