SM-N900 is Samsung Exynos variant.
Only runs 3G.
SM-N9005 is the Snapdragon 800 variant. It has 3G and 4G capability. It also records 4K video.
SM-N9002 is Dual-SIM.
SM-N900A (AT&T), SM-N900V (Verizon) are US variants with locked bootloaders. Stay away from them.
SM-N900T (T-Mobile), SM-N900P (Sprint) are also US variants but unlocked bootloader. Only 3G works.
Download the app called 'Phone Info Samsung', it'll tell you if the device is refurbished or not.
I suggest the SM-N9005. Best variant.
Official international variant. Go for it if it's a good price.
Other options in 25k include Xperia Z2, HTC One M8, iPhone 5 and Galaxy S5 (US variant).
Sent from my SM-N915F using Tapatalk