I scanned the specs for Asus Zen phone 4 copied it from NDTV Gadgets :
Asus ZenFone 4 sports a 4-inch WVGA (800 x 480 pixel) resolution display supported by a dual-core 1.2GHz Intel Atom Z2520 processor with Quad-Thread Hyper-Threading Technology and 1GB of RAM. The smartphone also features a 5-megapixel rear and 0.3-megapixel front-facing camera optics. The internal storage is not mentioned by the firm but it can be expanded up to 64GB via microSD card.
All is very similar to Nokia X . Except it has 1GB of ram and Nokia X has only 512mb. Intel Hyperthreading on desktop means the system sees a Quad core processor although it is in fact only a Dual Core Processor.
To summerize :
1. Nokia X : 512MB ram ; AZ4 : 1GB ram
2. Nokia X : Dual Sim ; AZ 4 : Single sim
3. Nokia X : Running Android ASOP . Dont support Play Store and Google Services Out of the box.
AZ4 : Running ZenUI skin on top of Android 4.3 Jelly Bean , upgradeable to Android 4.4 KitKat. Support
all google services out of the box.
Price both around RM350 .
Being a ex owner of Nokia X myself . Choose wisely

In Malaysia, The Asus Zenfone 4 is dual sim too, and it has 8 GB of internal storage. Asus Zenfone 4 is priced at RM299 while Nokia X is priced at RM399. It is a tough choice to choose between this two.