It's also different from Redis because Redis is intended to be ran as a server (it stands for Remote Dictionary Server). This is ran entirely as a process and communicates via IPC; other machines can't reach the database, only the local machine. This is a big reason for why it's very fast. However, it also means you can't distribute the database across multiple servers.
You could think of it like a very fast NoSQL Sqlite, I guess.
It would require adding a lot more code to allow for typical interprocess communication.