A creative process represents a very specific fusion of a process (a recurring workflow) and a project (a unique commission or assignment) among creative professionals such as designers, illustrators, writers, copywriters etc.
Experienced, top-notch creatives employ and develop their unique creative process to fulfill various creative assignments reliably, no matter how wildly different these may be. While inexperienced creators often consider the creative process to be something magical, even sacred, those with experience have gradually adopted diverse methods or workflows that help them to achieve satisfactory results in their creative work repeatedly and reliably.
Creative processes differ from typical workflow processes mostly in that they are less linear and are more likely to be comprised of successive phases and their respective methods, rather than a series of particular steps.
One great example of the creative process in an article about the Creative Checklist developed by Tomas Vachuda. There are also lots of books for creative professionals about the creative process, such as Steven Pressfield’s great take on it in The War of Art or you can peek into the remarkable compendium of habits perpetuated by great creators in Daily Rituals: How Artists Work by Mason Currey.