This ecosystem is super confusing. Here is the low-down:
- LevelDB is a (K/V-Store) database
- leveldown is a NodeJS binding.
- levelup is another NodeJS module, which wraps leveldown. However, it allows leveldown to be replaced with another backend.
In this way, you can use a single library and API – levelup – but with all kinds of different storage backends, from Redis, to SQL databases.