Rajnikanth appreance with a black skin tone, with average looks and physic, like a normal Tamilan helpful for him connecting with normal tamalians and the kind of Roles he do like angry, energetic, hardworking village man, a normal poor man, Connected well with B and C centres audience, some examples are, his roles in movies like muratai kalai, padkiathavan, Panakaran, Thalapathy, Mannan, Velaikaran and Annamalai.
Kamal Hassan is always more than a super star, he is an artist, He never bother about hits, flops fan following and box office collections, always tries to do something different and new, which is liked primarily by A center auidence, he have larger than life looks and fair skin tone, so these things makes not him to connect to much from B and C centres audience comparing to Actors like Vijaykanth and Rajnikanth.
So Rajnikanth is a hero for B and C center auidence, While Kamal Hassan is a hero for A center auidence, Generally B and C centers are referres to Villages and Small town, A centers are referres to big developed cities, At Rajani Kamal time, most part of the Tamil Nadu area clearly comes under B and C centers.
Rajnikanth always concentrate on to stay at top, to maintain his super star dum he knows what his auidence need from him, never Tries to do any thing different, depends upon more Remake movies, which are huge hit in other languages, some examples are billa, thilu mulu, panakaran, padkiathavan, Velaikaran, guru shiyan, mapallai, Dharamadhurai, Mannan, Anamalai, Muthu, basha and Chandramukhi, are huge hits, which satisfies his auidence, which are Remake movies from other languages.
Kamal most of the times Tries to give something new from his movies, and many times he also have faced box office failures due to this, Anabe sivam, Aladhavan, gunna, Hey ram are some examples