I buy both. But if a blend is offered in bulk and I like that blend, I will buy it in bulk.
I have smoked several different tobaccos that are offered in tin and bulk in both the bulk offering and the tin offering and there is no difference except, like Ohin3 said, that the bulk may be a little dryer than the tin.
This is another myth that sometimes happens in pipe smoking; that tinned version and bulk version of a blend are different. They are not. They are the same exact blend just packaged differently.