different major products formed why?

srry... forgot...
"there's no use of asking the questions here..." :P

well the answer is probability factor...

for cl , 1 degree : 2 degree : 3 degree - 1 : 3 : 5.8
for br, 1 degree : 2 degree : 3 degree - 1 : 80 : 1600

got the answer from one of my friends

Could you answer the cause or such degree of variation in the Probability factor?

Reactivity vs selectivity. Google it or read Morrison and boyd.