Ethics is do to with morality – what is right and what is wrong. For example, it would be unethical for a company to pay bribes to win contracts or to engage in industrial espionage.
CSR is considers to what extent a company owes responsibilities to parties other than shareholders and in excess of what the law demands. So, should an airport, for example, voluntarily pay for sound-proofing in nearby homes? Should a manufacturer go further than the law demands in providing health cover or health screening for its workforce?