Hi Baracatt! Thanks for reading!
Well spotted — JTBD have a lot in common with behavioural archetypes (BA) because both frameworks are outcome-oriented. I wouldn’t use them interchangeably, but they complement each other nicely and one can be more relevant than the other depending on the kind or stage of the project i.e. for a Discovery when you need to communicate a rounded picture of different user types, their contexts and create empathy with stakeholders — I’d use BA; for alpha development, when you think about functional details — I’d pick 1–2 archetypes and turn their needs to job stories for the dev team.
In service design projects, there is not just 1 job that a product fulfils. At different steps of a journey with a service, the user may have multiple JTBD/user needs. That’s why first I create the BA and then plot their JTBD on a user journey map for a more comprehensive picture. I touch on this in my other article on how to apply behavioural economics to the design process, if you’re interested