The LG K10 is the largest among the two handsets, offering a 5.3-inch IPS display with 720 x 1280 pixels, and a 2300 mAh battery. Depending on market, the smartphone will have LTE, or 3G-only versions, powered by different processors: either quad-core, or octa-core (unknown makers). The phone's RAM (from 1 GB to 2 GB), internal memory (from 8 GB to 16 GB), and cameras (from 5 MP on the front, to 13 MP on the back) will also vary by market.
As for the LG K4, this sports a 4.5-inch display with 480 x 854 pixels, and is presented as offering "best-in-class practicality" (we're not really sure what LG means by that). The handset has LTE connectivity, further featuring a 1.0 GHz quad-core processor, 1 GB of RAM, 8 GB of internal memory, and a 1,940 mAh battery. There's a 5 MP camera on the back, while the front camera is a 2 MP one with Gesture Shot (lets you take selfies with just a hand gesture) and Selfie Light (the display lights up when you want your selfies to be brighter).
In South Korea, where the LG K10 was released earlier this month, the handset costs around $166, so we expect global prices to be similar. Naturally, the LG K4 should be significantly cheaper.
LG didn't say anything about the launch of the K10 and K4 in North America. Anyway, the company is already selling a K Series smartphone in the US: the K7, which is offered by Boost Mobile under the name LG Tribute 5.