Samsung announced two versions of its Galaxy S 4 phone, one with the Exynos 5 Octa and the other with the Qualcomm Snapdragon 600, it was believed that the Exynos 5 Octa be compatible only with 3G networks. The LTE model would ship with Qualcomm's LTE-capable, quad-core Snapdragon 600.
That was apparently wrong. Both the Exynos 5 Octa and Qualcomm Snapdragon 600 version of the Galaxy S support LTE. So why make two versions. Speculation is that Samsung cannot make enough Exynos 5 Octa to meet the demand.
GSM Arena benchmarks show the Exynos 5 Octa outperforming the and Qualcomm Snapdragon 600. The Qualcomm Snapdragon 600 could be a little more power efficient since the LTE modem is a System-on-Chip solution, while the Exynos 5 Octa most likely has a separare chip for the LTE modem. On the other hand, the Exynos Octa 5 uses two pair of quad core chips. One for intensive operation and a more power efficient second quad-core chip for less intensive tasks. This might be enough to match or out perform that Qualcomm version.
The Qualcomm Snapdragon 600 version of the Samsung Galaxy S 4 performed very impressively in the battery life tests. Will be on the lookout for battery life tests of the Octa 5 Samsung Galaxy S 4.