No apology necessary <3.
i was also looking at a zenfone, but the ZX551ML (i dont think the S is available to me unless i unlock one and switch cellphone providers) the only real difference from a technical standpoint is that the S has a octa-core 2.0ghz cpu, whereas the ML has quad-core 2.5ghz, since you are in india both models come with 4gb ram unfortunately asus decided to release it with 65 bloatware applications, but cleaned stock roms are already in the dev process for it.
I was pretty impressed with zenfone after a detailed review!
http://www.pratapj.com/rich-text/asus-zenfone-3-max-picture-perfect/