No, non interchangeably.
Nel mio lavoro mi occupo dello sviluppo di siti web. (you can't use "posto")
vado a fare un lavoro. (you can't use posto)
posto is like workplace (it's the short form of "posto di lavoro") and lavoro is like work/job with the verb "lost" for example they can be used interchangeably, because if you will lose your job you also will lose your workplace"