What is the basic difference between traditional 3D and digital 3D?
As you'll be seeing in the attachment, it is used on major sites like artstation! www.artstation.com
I've some ArtStation experience, and I can tell you that you choose a "medium" on uploading project images, 360s, sketchfab links etc, and there's precious little or no textual guidance between the two types of 3D medium available to you in process.
Early on in ArtStation's life, you'd see that the "Traditional 3D" medium stuff was mostly literally physical sculpture or design maquettes - executed in clay or wood or other physical media. It's still true that the majority of 3D work listed as "Traditional 3D" is actual physical sculpture, but as the tagging of projects is up to the uploading artist, it's not policed, and so there is a certain degree of errata; it's also possible that the understanding of the meaning may be slowly losing relevance to younger artists.
I'm afraid I at least cannot agree with Joshjurg's proposed definitions, as I see rigged models in the "Traditional 3D" alongside clearly sculpted in-pose models - and I also see those same sort of sculpted in-pose models in "Digital 3D" and they're clearly not likely to be rigged with a heat bind mesh in those contorted poses unless someone's willing to undertake tens of hours of weightpainting just to make those rigs only somewhat useable.
I think it's supposed to mean exactly what it seems as though it would: there are broadly two categories: Traditional vs Digital and each is bifurcated into subcategories of 2D and 3D for ease of sorting/searching, where Traditional refers to all the media and techniques we all learned in art school from dry brush and gesso, pen and ink, charcoal, oil pastels and watercolours to additive and subtractive sculpting, lost-wax casting, burnishing, brazing; and where Digital refers to all computer driven media from CAD and BIM through Modo, Maya, 3DS, Houdini, C4D and procreate, sketchbook, Photoshop.
I can't verify where I remember hearing this from, but Traditional 3D objects are 3D CAD objects that have been modeled for and rendered for static viewing.
Digital 3D Objects are rigged for motion, walk cycles, particle effects and environmental interactions.
Here's a link to a relevant wikipedia article on Skeletal Animation: https://en.wikipedia.org/wiki/Skeletal_animation
In a nutshell, (I believe) Traditional 3D is created for only a single frame still image and Digital 3D is created with animation and interaction in mind.
I presume you could test this by downloading samples.
One of them starts with t and the other starts with d - that's the main difference in Artstation. There's other answers which can present common opinions outside Artstation or even something that Artstation may have originally wanted.
Artstation is a website where people can can keep themselves and their works visible. When one tags himself s to both digital and traditional 3D, there's 100% more tags that can show him when compared to only other of 3D tags is used.