How is the geography in south asia different from the geography in north africa

Desert and steppe lands cover most of the land of North Africa and Saudi Arabia. 
Great Desert of Rub'al Khali: This is also a big desert region like the Sahara desert. It virtually has very little to no vegetation what so ever. The sand dunes are the worlds largest because of the strong winds, some of the dunes reaching up to more than 2000 feet in height. In the desert temps vary drastically between the daytime and nighttime. 
African Plate/Arabian Plate: A rift formed by these two tectonic plates separates Africa and Southwest Asia. The African and Arabian tectonic plates are essentially moving away from each other. The rift which began to form over 12 million years ago is now occupied by the Red Sea. The Arabian Peninsula lies to the east of the rift. There the mountains are bordering the rift in the southwestern corner which can rise up to 12,000 feet.