I found this explanation on wikipedia “Digital sculpting, also known as Sculpt Modeling or 3d Sculpting, is the use of software that offers tools to push, pull, smooth, grab, pinch or otherwise manipulate a digital object as if it were made of a real-life substance such as clay.” Is it possible to refer to using ZSketch as “Digital Sculpting” too? I am writing thesis and I need to use the term properly 
ZSketch is a form of digital sculpting, yes.
If Digital Sculpting is Ford, then ZSketch is a Mustang, ZSpheres are a Neon, etc. They’re all different cars, but also all Fords.