Andrew Hodgson published a post on ArtStation that explains the difference between the two definitions.
After i uploaded the wireframe of my most recent aircraft and strongly suggested people DO NOT use it as a reference for how to model correctly, i received a lot of questions asking what i would do differently and why it matters. So i took a few pieces of my aircraft and rebuilt them to illustrate the difference between a concept mesh and a sub-d production mesh (for film). When i self taught myself 3d i had no idea what i was doing and how i was meant to properly model so something like this might be helpful to some people. I wanted to write more in here but there is a type limit so a brief explanation is at the bottom.
The post is concluded with a written breakdown by the artist:
Make sure to check out his portfolio here.