The 'Gangs of Wasseypur' movies were game-changers in the Bollywood 'gangster' genre movies in a lot of ways. They brought the stage of gang activities out of the city of Mumbai and focused on a growing backwater town of Jharkhand. The 'gangs' of Wasseypur, as the movies demonstrate, functioned on different ideas, circumstances and objectives than those of Mumbai (quite understandable due to huge circumstantial differences the movies' narrations expertly explain) which made for an interesting story. The movies follow a bundle of interrelated stories centered on memorable characters which have a stem in the progression of the Khan family's intergenerational struggle against Dhanbad's undeclared strongman and overlord Ramadhir Singh. The main protagonists of the two films are father and son- Sardar Khan and Faizal Khan- who have influenced each other's characters and have gone through the same struggle of dealing with the overbearing presence and power of Ramadhir Singh. However, a cursory look inti the films will reveal a number of differences that the mostly similar father and son have. It will be a fun exercise to make a list of those differences. So, let's get going with it!
Firstly, Sardar Khan is someone who grew up an orphan but had the support and care of his late father's assistant Nasir and the continued friendship of Nasir's friend Asgar. Sardar's operations were carried out with the assistance of these two upon whom Sardar could undoubtedly place his trust. On the other hand, Faizal was not orphaned as a child. However, due to his father's affair and remarriage with Durga he had to grow up virtually fatherless. When he caught his mother Nagma cheating on Sardar with Nasir, it shattered him and moved him away from his family mentally. Early on in his youth he was subjected to a cruel betrayal by Fazlu who he considered his only true friend. All this shaped Faizal to be a loner and he had the tendency to do most of his important jobs himself and alone for fear of betrayal. This, in the end, backfired and sealed Faizal's fate.
Secondly, Sardar had proclaimed early on that the sole purpose of his life was to crush Ramadhir Singh who had 'unjustly' (that's a story in itself) killed his father Shahid Khan. His stance regarding Ramadhir was, due to his burning hatred towards him, openly confrontational. Although Sardar made calculated and cautious moves against Ramadhir, in an apparently perplexing contrast of character he always jumped at the chance of showing that he had made those moves. This, on one hand, gave him a lot of power as Ramadhir's enemies flocked to him both in Wasseypur and Dhanbad, but it also made him an easy target, which ultimately contributed to his demise. Faizal, however, learnt from his father's mistake. He expertly played the double card of openly negotiating peace with Ramadhir while taking out his men who had been directly involved in the killing of Sardar. This confused his adversaries and made him less obvious of a target. Faizal's character has a cold calmness and patience about it that Sardar's character lacked. However, it slowly became clear that Faizal, unlike Sardar, was not fixated on killing Ramadhir. The battle for vengeance was his father's, not his. In the end, he admits that he was pulled into a conflict that was not his to begin with.
Thirdly, although Faizal is more level-headed and cunning than Sardar, the former lacked the latter's business sense. Sardar had erected an illegal business empire rivalling Ramadhir's. However, Faizal could maintain this empire solely through intimidation as he had very little understanding of finance. This created a weakness in Faizal's operations that Sardar's never had, which was duly exploited, albeit indirectly, by Ramadhir.
Fourthly, the most glaring feature of Sardar Khan's character was that he was a womanizer. During her first pregnancy, Nagma caught Sardar in a brothel. She, after a lot of struggle, had to come to terms with the fact that Sardar could not be stopped from visiting brothels. However, he went one step further and married a Bengali Hindu girl named Durga, leaving Nagma and his two sons Danish and Faizal to virtually fend for themselves. He later realized Nagma's pure love for him and came back, this time leaving Durga and their young son to face the uncaring world by themselves. This reckless love life finally came to bite Sardar in the back as Durga played a key role in his murder. Faizal, on the other hand, had seen the poisonous fruit of reckless lust in his impoverished childhood. Hence he was always faithful to his wife.
So these are the principal differences between Sardar's and Faizal's character. It can't be helped but to observe that many of Sardar's decisions shaped Faizal's character even though he was an absentee father. In fact, Sardar's mistakes dragged Faizal deeper into his father's conflict and eventually took his life.