Conventional banking: I lend you 100 riyals today. You have to pay me 110 riyals next year. That is for an interest of 10 riyals.

Islamic banking: I buy your pen for 100 riyals today. But you have to buy it back after one year for 112 riyals, that is for a profit of 12 riyals.

The only difference is 2 riyals.