Consider a hypothetical example in which you sell both a put with a strike price of 90 yen and a call with a strike price of 110 yen for a premium of 2 yen each. You receive 4 yen in total. If the price at expiry is between 90 yen and 110 yen, the 4 yen is your profit, and the break-even points are 86 yen and 114 yen. Beyond the break-even points you make a loss, and the loss on the upside has no cap. If you buy both instead, the profit and loss is reversed, and the 4 yen paid is the maximum loss.