Author here. We actually know the Citus guys pretty well, and spent some time comparing notes last week at PGConf (Hi Ozgun!). We're quite friendly.
At a high-level, Citus is solving a very different problem: general analytics and transactions at scale, ideally for B2B applications. On the other hand, Timescale is laser focused on time-series workloads.
At a high-level, Citus is solving a very different problem: general analytics and transactions at scale, ideally for B2B applications. On the other hand, Timescale is laser focused on time-series workloads.