The underlying queue is very similar. See this comment, which details how we're different from a library client: https://news.ycombinator.com/item?id=39644327. We also have the concept of workflows, which last I checked doesn't exist in River.

I'm personally very excited about River and I think it fills an important gap in the Go ecosystem! Also now that sqlc w/ pgx seems to be getting more popular, it's very easy to integrate.