The X2-CU is powered by an octa-core processor that’s most likely made by MediaTek, while the X2-TO has a dual-core 2.2 GHz processor. Other than that, their features seem to be identical, including a 5-inch IPS display with 1080 x 1920 pixels, 5 MP front-facing camera, 13 MP rear camera, 2 GB of RAM, and 16 GB / 32 GB of internal memory.
Both Lenovo X2 variants run Android 4.4 KitKat, and they’ll probably be released soon in China (Lenovo’s home country). At the moment, we don’t know if Lenovo plans to make any of them available internationally, but we'll let you know if we hear anything about this.
source: TENAA (translated)