What is the difference between using opencv-python and building from source?

I hope you mean https://pypi.org/project/opencv-python/ because anything listed on conda tends to be unmaintained junk.

that package lacks CUDA, because that’s notoriously fussy about its environment, and it can’t come with non-free algorithms due to licensing.

if you redistribute a binary package, you’ll be subject to the legal stuff too. I doubt that you’ll need any of those non-free algorithms.

the DNN module has many possible backends. OpenCL tends to work anywhere.

practically, there are no limitations to you and your use case.