If you sell (short) a call, the maximum profit you can make is what you received from the sale. The maximum loss is unlimited.

Say you sell a call to buy 100 shares for $50 to someone for a price of $2. If the stock is any amount below $52, you keep up to $2. If it goes above $52, you lose $100 for every point it goes up, because you have to buy the stock for that price and turn around and sell it to your buyer for $50. There is no limit on how high the price can go, so your loss potential is unlimited.

If you buy a put the maximum profit you can make is the difference between your stike price and zero, times 100.

On that same stock, if you buy a put you are buying the right to sell at a given price. Therefore, you make money if the price falls. Say you pay $2 for the right to sell at $50. You make $100 for every point that it falls below $48. That means your maximum profit is $4800. If the stock goes up, the maximum you can lose is the $2 you paid.

HUGE difference between the two.