Thanks for getting in touch and welcome to the CoSpaces world!
There are quite a few differences between Maker and Edu; Edu is specialised and geared towards education and teachers in the sense that it has added classroom functions like creating assignments and monitoring student process in real time. Edu also has a larger array of features such as the physics tool and full access to all of our pre-rendered characters and objects. There is an annual cost for Edu (after a free two month trial) whereas Maker is free but doesn’t have as many features or characters/objects.
It is indeed possible for you to upload your own 3D models - CoSpaces is compatible with .stl files, and we are also working on the inclusion of .obj and .fbx, as well as the textures.
In regards to the size of the world, this would depend on how you scale the objects inside. It’s possible to create incredibly large worlds.
Please feel free to trial all the features with CoSpaces Edu at https://cospaces.io/edu/. We also have a plethora of youtube tutorials that can help here: https://www.youtube.com/channel/UC6VsnmaKQ9MNRpJbFsIhoGw
Thanks very much