Bitcoin Q&A: Differences Between Grin and Beam?

What are the differences between Grin and Beam, implementations of the MimbleWimble protocol? Why has there usually been a trade-off between privacy and scalability? Grin is an open-source research project, with no pre-mine, a continuing issuance model, is developed by volunteers, and is written in Rust. Beam is more of a commercial product with a foundation that organizes funding and development, with a limited supply, and is written in C++.