Check out this early comparison between the LG G2 and the Samsung Galaxy S4. The G2 features a slightly larger display and has its physical buttons located at its rear. The G2 has a 13 megapixel camera similar to the one on the Galaxy S4 but includes optical image stabilization with the promise of blur free photos. The Galaxy S4 adds the microSD storage expansion while G2 users will have only their internal storage.
source - PhoneArena