iCloud Photo Library, is it like photobucket?

If my pictures are backed up to the iCloud Photo Library, can I delete them off my iPhone to free up space and still be able to access my photos at iCloud.com/photos? Or do I lose my content from the iCloud Photo Library once I remove my photos from my device? I guess the real question is, does the iCloud Photo Library work as a Photo back-up (i.e. photobucket, flikr, shutterfly, dropbox)?