How many types of 3d models are there?

There are several different types of 3D models, including:

Polygonal models: These are models made up of a large number of small polygons, which are typically triangles or quadrilaterals. They are used in computer graphics and are often used for 3D printing.
NURBS models: These are models that are defined by a series of mathematical equations, which are used to create smooth, curved surfaces. They are often used in industrial design and engineering.
Subdivision surface models: These are models that are made up of a low-resolution mesh that is then subdivided to create a smoother, more detailed surface.
Voxel models: These are models that are made up of a grid of tiny cubic cells, each of which can be assigned a color or other property. They are often used in video games and other interactive applications.
Sculpted models: These are models that are created by digitally sculpting a digital clay-like material, using a variety of tools and brushes.

Overall, there are many different types of 3D models, each of which has its own unique characteristics and uses.