The pencil is probably the oldest type of writing instrument, which is still in use. In his way to write it is offering the widest range of use-cases. Starting from simple writing, over technical drawing, up to creating paintings. Therefore, the pencil can be found in different versions depending on the scope of application. This can influence its appearance. You can get it in the classical wooden style or as a fine-mine-pencil, optically quite close to a ball pen. On the other side, based on the potential use-case, the softness of the mine can have extreme soft- or hardness. For example, technical drawing will request more harder mines, whereas painter prefer more soft mines to have more freedom of design.
And yes, you will find pencils also in different mine-width, like every other pen. The possibilities of widths, based on the broad range of usability, can be very versatile. The most common mines are 0.5 mm and 0.7 mm, when you focus on writing.