The answer is ownership.
Revenue refers to the income generated by a business from its normal business operations. While revenue can vary between different types of business structures, it is not the primary distinction between proprietorships, partnerships, and corporations.
Costs are the expenses incurred in the operation of a business. Similar to revenue, costs can differ based on the business structure, but they are not the primary factor that distinguishes these types of business entities.
Ownership is the primary characteristic that distinguishes proprietorships, partnerships, and corporations. In a proprietorship, the business is owned by a single individual. In a partnership, the business is owned by two or more individuals who share ownership and responsibilities. In a corporation, ownership is divided into shares, and shareholders own the corporation. This distinction in ownership structure is fundamental to how each type of business is organized and operated.
Profit is the financial gain realized when revenue exceeds costs. While profit is an important aspect of any business, it is not the primary characteristic that differentiates proprietorships, partnerships, and corporations.