I wonder how is this different from Thanos or Uber's M3

There are two versions of VictoriaMetrics: single-node and cluster. Both versions are easier to configure and operate comparing to Thanos, Uber M3 and Cortex.

Single-node version is the easiest from operations point of view - just run a single binary with the desired command-line flags. VictoriaMetrics is resource-optimized, so it can easily substitute moderately sized cluster built with competing solutions such as Thanos, M3 or Cortex.

Cluster version has simple architecture (KISS) with the minimum number of moving parts. This simplifies its' setup and operation. Read more here - https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/FAQ#... .