It's a difficult question to answer because it's sort of like comparing apples and oranges. They seem similar because they expose similar types of data but Falco is much more powerful than osquery. For example Falco's front-and-center value add is detection and alerting, osquery does neither.
It's best to think of osquery as a more simple observability tool. It mostly presents an abstraction layer for data and OS concepts. And osquery presents a LOT of data across various operating systems. You need to integrate osquery with a product suite to be able to compare to Falco/sysdig.