fad. First, some similarities:
1) A growing realisation that some new perspective or 'lens' had to be applied to how business operates
2) Interdependencies - internal and/or external to the organisation - being key
3) Crossing or spanning organisational boundaries
4) A complex topic, with no absolutely correct answers
5) Human behaviours and corporate culture being core aspects
6) Existing mental models (and even business models) hampering progress
7) Few existing, commonly recognised or standardised qualifications for practitioners
8) Challenging to define or explain what the terms mean - they can mean different things to different people
Now, some differences:
1) KM was generally an organisation-specific choice in response to its own internal context and capabilities, whereas Sustainability Management is (mostly) a response needed by many (and perhaps all) organisations to tackle issues or symptoms that arise externally. If they don't respond, including responding collectively, many will go out of business through resource depletion (or, ultimately, be put out of business by Governments who will intervene in markets to change the rules or "licence to operate")
2) KM was regarded as somewhat 'highbrow' or 'intellectual' whereas Sustainability Management, although it does have elements of earth science and engineering in it, is essentially quite a straightforward concept and can be encapsulated in many different but widely accessible ways, for example in a tag-line such as "save the planet to save ourselves"
3) There are an increasing number of recognised qualifications in Sustainability Management, including Masters level ones.
4) Sustainability Management is interwoven into many companies' Corporate Social Responsibility models
Conclusions:
The jury is still out on whether Sustainability Management will be here to stay or will eventually join the long list of has-been management fads alongside Knowledge Management. Even if it does fade away in the longer-term as a discrete discipline, I think it will need to continue to be a hot topic for several years (perhaps decades) until it is 'internalised' into every human decision that impacts on resources. I suspect that, in the same way that every business activity has to have a financial footprint (which is maintained and monitored by accountants), there will, from this point forward into the foreseeable future, need to be sustainability professionals looking after organisational sustainability footprints. Are we seeing, therefore, the birth of a new profession?