What's the difference between a canister stove and an integrated boil system?

A bare canister stove (like the MSR PocketRocket 2 or SOTO WindMaster) is just a burner that screws onto a fuel canister and supports your own pot. An integrated system (like the Jetboil Flash, MiniMo, or Stash) packs the burner, a heat-exchanger pot, and often an igniter into one nesting unit, trading flexibility for faster, more fuel-efficient boils.