Qualcomm confirms that the '600' is the other processor for the Samsung Galaxy S 4

Just like it did with the Samsung Galaxy S II and Samsung Galaxy S III, the Samsung Galaxy S 4 will be powered by two different processors depending on where you live. In Europe and overseas, Samsung will eat its own cooking with the quad-core 1.6GHz Samsung Exynos 5 Octa powering the handset with the PowerVR SGX544MP3 GPU crunching graphics. 

On Friday, Qualcomm confirmed that its Qualcomm Snapdragon 600 processor will be under the hood in the U.S. and Canada. This info was leaked in late February. The Adreno 320 GPU will be crunching the graphics. For the Samsung Galaxy S 4, the quad-core processor will have a 1.9GHz clockspeed. The same quad-core processor is used on both the HTC One and the LG Optimus G Pro but set at a slower 1.7GHz speed. 

The Qualcomm Snapdragon 600 powers the U.S. version of the Samsung Galaxy S 4

The Qualcomm Snapdragon 600 is said to offer 40% better performance than its predecessor, the Qualcomm Snapdragon S4 and was introduced at CES in Las Vegas. The official word about its inclusion in the just announced superstar handset came from the big chip maker when it said in a press release that "We are proud to say that the newest Snapdragon 600 processor is at the heart of the Galaxy S4 in select regions," and later sent an email to Ars Technica confirming that the U.S. version of the Samsung Galaxy S 4 is powered by the '600'.

Last year, the international version of the Samsung Galaxy S III  (GT-I9300) carried a quad-core 1.4GHz Samsung Exynos processor while the U.S. model carried a dual-core 1.5GHz Qualcomm Snapdragon S4 Pro (to be fair, the U.S.models also carried 2GB of RAM as opposed to the 1GB on the international model). The Samsung Galaxy S II had different chips in different models within the U.S. market. For example, the T-Mobile version of the phone had a dual-core 1.5GHz Qualcomm Snapdragon S3 while the AT&T and Sprint variants were powered by a dual-core 1.2GHz Samsung Exynos processor.

source: Qualcomm,  ArsTechnica