This is, what i understand of it from marketing course at uni.
Stock are tangable objects, such as iron ore & coal. If you buy stock what you are really buying is loads of some item sitting in storage someware. So playing the stock market is
EXTREMELY risky & complicated... after you've bought stock you do not sit around waiting for them to increase in value, you sell it as
SOON as possible. Selling your stock to someone willing to pay a little extra than what you purchase it for is not good enough... you need to take into consideration their location, how much is it going to take to ship it their, trade policies, embargo's & stuff like that and of coarse the location of your stock.
Think of the stockmarket as a B2B version of ebay, a much more complicated version of ebay... & in fact there are other on-line auctions that are restricted to businesses alone, for trading stuff like hardware, office supplies and so on...
Shares on the other hand are when you buy part ownership of a business, only a very small part, as whoever has 51% gains control over the company and can basically direct it as they see fit. when you buy shares the company will offer a negotiable percentage & price to a limited number of people... the company can charge whatever they like for the percentage but as long as the buyer is willing to risk that amount. After you've bought shares you just sit around and wait, as the company increases in size & profit so does the return of your shares e.g. if you invested $100 and the company increased by 10% your now $10 richer if you pull your shares out of the company.
however there is a huge risk with shares, when you buy shares the company is free to do what it likes with that money... if they spend it, then the business goes broke & files for bankruptcy the chances of you getting that money back is zilch, also another thing to watch out for is people selling shares to companies that they don't own or don't actually have the shares to sell you and various other schemes to basically screw you over.
why a fish market? ... pretty self explainatory. one sells fish while one sells stock. The most obvious example of stock is cattle. The current droughts in aus have made their stock worthless, you can pretty much buy a few hundred cows for $50 possibly cheaper... the problem is having somewhere to put them & how many of them may need to be put down.
To me stocks & shares are something that only the rich have the money to risk on.