Shapes and polygons
Polygonal modelling is for many aspects the digital equivalent of traditional sculpture. It is in fact very much suited for organic and natural shapes and it is the standard technique for the creation of artistic and aethetic content.
CAD design
On the opposite side of the spectrum we have CAD creation (Computer Aided Design): precise measurements and exact geometries, perfect for industrial production of functional components.
Photogrammetry
Photogrammetry is a technique that allows to create tridimensional models starting from photographs. The level of detail is impressive, and the applications for this technique are very numerous.
Visit my Thingiverse profile to see some of my 3D printing projects!