What is Opendoors business model?

Could you please explain to me the underlying structure of Opendoor's business model? I'm particularly interested in understanding how they make money and what sets their approach apart from traditional real estate agencies. Additionally, I'd like to know if there are any potential risks or challenges associated with their model that investors should be aware of. How does Opendoor ensure a seamless experience for both buyers and sellers, and how do they utilize technology to streamline the process?