A Public Limited Company is a company that has hundreds of shareholders. A Private Limited Company is a company that has a handful of shareholders. Investing n a Public Limited Company is open to the general public, anyone can buy shares, and sell when ever he wants. In a Private Limited Company, only the people in the close circle can invest, possibly the relatives and friends. The Public Limited Companies are the companies that have huge capital, think about the figures in millions. The Private Limited Companies have a comparatively small capital, something like $200-$300 K.
If you want to establish a Private Limited Company, you can easily do so by getting joining hands with a couple of like-minded people, raising capital from the people interested in business, and registering the company with the company registration office. The process of establishing a Public Limited Company is almost similar but you need a lot of investment. These companies have to work for a couple of years before they can open publically for investment.