A registered or sole proprietorship is a company where you are the sole owner. There is no legal separation between the business and yourself, which means that any profits or losses are your responsibility. This is the simplest and cheapest form of opening a business.
An incorporation or joint stock company is a more complex legal form than a sole proprietorship. It is a legal entity in its own right, separate from its shareholders. Thus the financial risks of the business will not directly affect the personal assets of the founders.