This week, Samsung's Galaxy S III phone will go on sale in the U.S. The Galaxy line has emerged as a leading competitor to Apple's iPhone. Here's a comparison of the two phones:

— Capacity and price:

Galaxy S III: 16 gigabyte model for $200, 32 gigabytes for $250 (prices higher through T-Mobile; 32 GB version not available through AT&T). Accepts microSD card of up to additional 64 GB.

iPhone 4S: 16 gigabyte model for $199, 32 gigabytes for $299 and 64 gigabytes for $399. Not expandable.

— Size:

Galaxy S III: 5.38 x 2.78 x 0.34 inches.

iPhone 4S: 4.5 x 2.31 x 0.37 inches.

— Weight:

Galaxy S III: 4.7 ounces

iPhone 4S: 4.9 ounces

— Camera:

Galaxy S III, iPhone 4S: 8 megapixels in back

— Display:

Galaxy S III: 4.8 inches diagonally. 720 X 1280 pixel resolution at 306 pixels per inch.

iPhone 4S: 3.5 inches diagonally. 640 x 960 pixel resolution at 326 pixels per inch

— Battery life:

Galaxy S III: Samsung does not say, but AT&T lists talk time as up to 8 hours.

iPhone 4S: Talk time is up to 8 hours on 3G, up to 14 hours on 2G. Internet works for up to 6 hours on 3G, and up to 9 hours on Wi-Fi. Up to 10 hours of video playback.

— Wireless carriers:

Galaxy S III: AT&T, Verizon Wireless, Sprint, T-Mobile and U.S .Cellular

iPhone 4S: AT&T, Verizon Wireless and Sprint Nextel at launch. Several regional carriers added since then.

— Release date:

Galaxy S III: Varies by carrier.

iPhone 4S: October 14, 2011

— Operating system

Galaxy S III: Android 4.0.4 (Ice Cream Sandwich)

iPhone 4S: iOS 5.1.1 (updated to phones in May)