Yeah good point. I think it's also different since the interruption is on your own terms - you've deliberately given yourself 5 minutes break from some task so that you be more focused over the lifetime of that task. You're (hopefully) not getting other tasks thrown at you which can take up precious mental resources or destroy context you've been slowly building up in your head.
I use pomodoros religiously, and you touched on one of the few gotchas of the technique; Never use your break to attend to other work, unless it's thoughtless. Can't say how many times I've lost the thread and been kicking myself because of mixed contexts.
