1) Business ethics is initially internally driven, sustainability is initially externally .
2) Business ethics are how you work every day. Sustainability is how your company works every day and how that affects others beyond immediate impact/customers. So in supply chain terms business ethics is Tier One, Sustainability is Tiers Two, three, four and beyond…
3) Business ethics was originally about the individual responsibilities of the businessman, the owner operator. Sustainability has always been about organisational or systems impact.
4) Both are subjective. Both are often viewed as absolutes: ethics gets confused with compliance, and sustainability is often viewed as purely environmental in application.
5) Business ethics is rarely seen as a strategic issue, unless a company becomes embroiled in a major scandal. Sustainability often begins as a tactical response to perceived or real external pressures, but quickly becomes a corporate strategy issue if taken seriously.
6) Corporate responsibility is often a bridge between the two: A business response to internal and public interest in ethical and environmental impacts of the company.
N.B. I’m aware point two is very arguable/problematic.