If I delete pictures on my camera roll, will they be deleted in iCloud

You asked the question twice two different ways, but know, when you use iCloud it syncs photos across all devices, if you delete a photo anywhere on any device it will delete it on ALL devices.

BUT, on your iPhone you can change a setting to "Optimize Storage" so on your phone if it needs space it will keep a lower resolution (Smaller File) and leave the original untouched on iCloud.

Hi

Options for managing photos on iPhone and for keeping copies elsewhere or backing them up include:

Enable iCloud Photo Library.

• Copies of all photos and videos on your iPhone are stored automatically in iCloud at their original size / resolution.
• You may also wish to turn on Optimise iPhone Storage. This frees up storage space on your iPhone by keeping space saving versions of all of your photos and videos on your iPhone and full size originals in iCloud. Files are optimised automatically, as required.
• When using iCloud Photo Library, deleting a photo or video on any device that is using the service also deletes it from all other devices that are using the service, including from iCloud.
• iCloud Photo Library - Apple Support

Import photos and videos to your PC:

• Import photos and videos from your iPhone, iPad, or iPod touch - Apple Support

If not using iCloud Photo Library, back up your iPhone using iTunes or iCloud:

• Note that a backup cannot be browsed or searched to see or open any of the component elements. It can only be used to restore your iPhone's content and settings in the event that your iPhone is erased or replaced.
• How to back up your iPhone, iPad, and iPod touch - Apple Support

You may find these support resources helpful:

• Taking and Managing Photos - Official Apple Support
• Manage your photo and video storage - Apple Support