How to tell the difference between the white iphone 4s and the white iphone 5?

Both look same to me.

There's a thing at the top. For iPhone 5 is circle for iohone 4s is a curved rectangle. Also iPhone is longer. Hope it helped.

The iPhone 5 I lighter in weight, longer, and the outside rim of it may not be silver like the 4

IPhone 5 is significantly longer and just a bit skinnier. Also, the charger for the iPhone 5 is completely different.

A white iPhone5
Has a camera at the top and the left side
Taller and skinner

A white iphone4s
Shorter and fatter
Has a camera on the side and 2lines one beside the camera and one above the one beside the camera

Well the iphone5 is flatter than the uphone 4s also the 5's screen is bigger.another different thing is that the back of the iphone 5 has a different design.another thing is that the iphone 5 has a different chargers it more little the iphone 4s has a wide charger input hope this helps.