STL is the de facto standard in consumer-grade 3D printing. It is a bare-bone format that describes the shape of the object by defining the coordinates of all the vertices of all triangles that a surface may be subdivided into.
This means that in STL any curved surface is represented with an approximation of many very small faces.
OBJ is also somewhat ...
Color is only displayed if you set MeshMixer to render VertexColor:
Color should be visible if VertexColor is active.
Meshmixer is a sculpting program, so it isn’t made for taking exact
measurements, creating mechanical parts, or creating architecture
Basic rendering options make pretty screenshots, but ...
3D files differ greatly in size and what they contain:
STL Stereolithography files were invented by 3D Systems to store surfaces. Originally it used ASCII text to store information by naming triplets of vertex positions for each triangle (facet). Since that got too large, newer STL are Binary, which is quite smaller.
Many programs can export them, their ...
If a general-purpose compression tool using a good compression algorithm, such as 7zip or gzip (for linux and command line enthusiasts) is not providing good compression it is not likely that your files can be compressed very much.
This applies to a wide variety of binary files beyond just 3D print files. There is always a fundamental limit on compression ...
While the STL-format can only describe your object aproximatively by those well known triangles, OBJ-files can describe parts of your object parametrically by curves. This can lead to a higher precision and be a huge advance with regard to scalability.
Which data format to choose depends, as always, on the application and the processes it contains. E.g. if ...