Earlier quoted context omitted.
It's like you understand the theory but not the practice of how this works? In reality, you "short" a stock by purchasing a Put option. For example, these are made up numbers, but if you thought Apple would tumble on earnings and wanted to short it, you'd buy, say, $525 put options. This is a contract to sell 100 shares of apple at $525. It's worthless if they trade above $525 but if it drops below, you're in the mon…
Shorting and buying put options are not the same thing.
For one thing, a put (or call) option doesn't even trade on the same markets (usually), has a lot less liquidity (usually), and depends on the supply of people willing to write contracts against positions they already hold. (non-naked) Options also have the effect of limiting any possible loss to the price paid for the option.
When you short a stock, your loss is potentially UNLIMITED. In practice, your broker will buy the stock for you with whatever cash you have on hand if the price moves against you.
That doesn't happen with options but you also don't get the huge sums of money to play with by borrowing against a stock that you don't own but are positive will dive into the dirt.
edit: explanation.