Thanks Tony. I posted the same question the IIBA forum and got an interesting response:
http://community.theiiba.org/vb/showthread.php?p=474#post474
- which makes a good case that, regardless of labeling, this is not necessarily just a turf thing. While their processes (eg elicitation, documentation etc), methods (eg workshops), and artefacts (requirements documentation, models, etc) may be more or less identical, BAs and requirements engineers/analysts etc are often not working on the same kinds of projects. While both often work on software systems, requirements engineering typically deals with large complex systems in which software is only a component, eg airplanes, naval vessels, automobiles, hydroelectric plants, etc.
This suggests that the difference in scale might involve a qualitative difference in approach and output, and Berenbach et al make the point that processes that work for a small number of requirements will not scale to, say, tens of thousands of requirements or more. (Barenbach spoke at the conference and made the further point that no one in industry or academia has successfully implemented a process yet that does work well with very large numbers of requirements.)
That said, the different labels are a very poor (and very confusing) way of distinguising between the two practices. Standard definitions of RE are not much help:
Requirements engineering is the branch of software engineering concerned with the realworld goals for, functions of, and constraints on software systems. It is also concerned with the relationship of these factors to precise specifications of software behavior, and to their evolution over time and across software families. (Zave)
And if I substitute the phrase 'business analysis' for 'requirements engineering' in 99% of the literature I've seen so far, it wouldn't make a substantive difference. Still, it's valuable to appreciate how projects of vastly different scale - including numbers of requirements, and numbers and variety of components (including hardware, software, social, etc) - call for different approaches to requirements elicitation, documentation, and management. Whether a REBOK (and I have a feeling there will be one eventually) will help illuminate those differences remains to be seen.
Bruce