The Lexus IS offers luxury features that the Mark X does not. Please go look up everything that the IS has to offer and then you'll see Mark X is not a luxury saloon. Mark X in Japan is not priced as a luxury saloon, its in the same price segment as an Accord, or Camry, neither of which are luxury cars (contrary to idiots-belief in Pakistan).
Lexus IS - Features & Pricing - Pricing & Options
Mark X "looks" luxurious to Pakistani people as we're deprived of better cars. Anyway, I'd pick the IS in a heartbeat over the Mark-X.