If you have fine hair, your individual strands are smaller in diameter, while coarse hair has a thicker diameter. When you run your hands through your hair, does it feel like there’s not much there? Keep in mind this does not necessarily mean you have fine hair, it may just be thin.
Having thin hair references the density of the follicles, or how close individual strands are to each other. When men are balding, the term used to describe the hair is thinning, because they have less densely populated hair in a particular area.