Query calls and responses don’t cost anything at the moment. But from what I heard there will be some ideas for pricing query calls in the near-ish future
The docs page is 100% accurate in cycles cost. The dollar amounts can change, but the XDR/USD pair hasn’t deviated much from the stated 1.3 exchange rate (1.35 at the moment)
I guess the cost difference stems mostly from the Ingress Message Reception field. Every call made from the outside to the IC is an ‘ingress message’. If you run an update call from another canister you don’t cause an ingress message.
This would give a baseline of 1200k + 590k cycles = 1790k cycles, plus payload of a few bytes (2k cycles each) and a little bit of execution sounds about right to me