I would say 2600 is more counter-culture / anti-authoritarian / political, and Phrack is more just about the technical stuff. To give a recent example, 2600 gave their support for BLM:
https://www.2600.com/node/37570
Which lost them a bit of support (although perhaps gained some as well?).
2600 is also pretty good at never missing an issue (quarterly), and also runs actual prints.