The terms shareholder and stockholder mean the same thing and can be used interchangeably. Stocks, or shares, represent partial ownership of a business. Each stockholder gets one vote per share, so the person or business who holds over 50 percent of the shares has the controlling interest.
Stocks are often part of mutual funds, but in this case, those who have bought the investment are not considered to be shareholders. Only the investment firm on title gets a vote. All stockholder names must be listed on a company's corporate ownership documents, and all shareholders must be informed of and have the right to attend all shareholder meetings.