Not comparable. Similar to Neo4j vs LatticeDB. Lattice's goals are simplicity, single file, super easy to start using. Surreal supports embedded mode, but my understanding is it is not a single file. Surreal supports a huge number of data models, Lattice is more focused. Surreal also appears to have a company behind it. Lattice is just me.

If you are looking for something lightweight and simple, choose Lattice. If you are an Enterprise looking for hosting, Enterprise support, and maybe a database that can handle all of your needs instead of a specific one, pick SurrealDB.

I hadn't heard of SurrealDB until your comment though, so take what I have to say here with a grain of salt.