Sure. There's definitely some overlap. Shenzhen is a smaller piece of the puzzle, designed to build and deploy from a single system at the point that a user decides to do so.
Distiller provides hosted continuous integration, building your code and running all of your tests every time someone commits to GitHub. It also allows you to push the passing build to an OTA platform (Testflight or Hockey) as a final step.
The difference is most notable in a team environment where everyone can have access to build results, including seeing the test results on a GitHub pull request before deciding to merge a set of changes.
Distiller provides hosted continuous integration, building your code and running all of your tests every time someone commits to GitHub. It also allows you to push the passing build to an OTA platform (Testflight or Hockey) as a final step.
The difference is most notable in a team environment where everyone can have access to build results, including seeing the test results on a GitHub pull request before deciding to merge a set of changes.