Work is such an important part of most people's everyday lives so it doesn't entirely make sense to talk about personal and professional ethics as separate entities. Individuals rarely leave their values and experiences at the door when they enter the office or the factory. There are some differences, though. Professional ethics tend to develop with practical outcomes in mind while personal ethics come from hearts and souls. It makes sense for a company to post a code of ethics and use this document as a marketing tool. It would seem pretentious and self serving for an individual to make a similar proclamation.
Acting ethically as a professional is good business practice. Most businesses are built on long term relationships and carefully built reputations, If your business dealings are fair and transparent, your customers and vendors will want to continue doing business with you, and they're likely to refer their friends and associates. For the typical small business person, it makes more sense to simply do good work and build your company by earning the respect and trust of your clients and business associates. Deliver the quantity and quality specified in your contract. Honor the terms of your agreements, even if you haven't put them in writing. Treat your employees with dignity and respect, and pay them as fairly as you can.
Acting ethically as an individual is good personal practice and it helps you to build strong relationships and sleep soundly at night. Personal ethical systems can be categorical, or geared towards doing good for its own sake. Personal ethical systems can also be utilitarian, or geared towards doing good for the sake of creating outcomes that improve quality of life for as many people as possible. Treating friends and neighbors with kindness can be the basis of a personal ethical system. Telling the truth is a personal ethical value as well, as is refraining from theft.
Some professions, such as medicine and accounting, require licensed practitioners to adhere to a specifically articulated code of ethics that helps to create legitimacy for the profession as a whole. Certification and membership in the group of professionals is contingent on following this code and professionals who are found to violate it risk losing their licenses. Following such a professional code of ethics is a practical matter because it is necessary for job stability, and it's also a matter of personal and professional integrity.
Many companies post a code of ethics on their websites or at their brick and mortar locations. These documents may be sincere declarations of values and purpose or they may be marketing tools aimed at winning the business of potential customers. Whatever the motivation behind these statements, a written code of ethics is unlikely to earn long time support from clients unless the proprietors and staff actually implement the stated ideals.