I'll give you my answer as a lawyer. I don't know of any significant difference between the terms firm, company, enterprise, or business. Although they do have somewhat different uses, depending on the trade one is in, they are essentially all the same legally. So, there are "law firms" but not "law companies or enterprises". Insurance companies usually use the term "company" rather than firm or enterprise. That's just the language part of it. Now, the BIG difference is in what a corporation is. A firm, a business or an enterprise can and frequently is a corporation (but not necessarily). A corporation is, in the US, what is called a "non-natural person." It seems odd, but a corporation is a "person" in American jurisprudence. It's subject to its own tax, it can go into bankruptcy, and so on. It has to be created, given life so- to-speak, through what are called "articles of incorporation" and it can be dissolved (ended). It's operated by people (one or more, sometimes large numbers) and the owners of the corporation aren't personally responsible for its debts. They may fund it, but if it fails, the owners/shareholders aren't responsible for its failure personally and can't normally be personally sued over its debts and losses (there are some exceptions, however). Corporations, because they are legally treated as "people" can sue in their own name, or be sued. They can be small, medium or large in size. Their ownership interests can be publically traded (those are called shares), sometimes if they meet strict and complex regulatory rules, and they are often called "limited liability" companies because, again, their owners aren't responsible for the corporations debts beyond the owners investments in funding the corporations. This is just a simplistic overview, since the subject of corporations is an entire semester's course at a US law school and usually involves reading a 1000 page book on the ins and outs of how they operate and are created.