What is the difference in these two logics used to solve this question? In a school committee comprising 12 members, there are exactly two students from each of the classes from class 7 to class 12. In how many ways can a sub-committee of four students be formed, such that no two students in the sub-committee belong to the same class?
First logic
There are 6 classes in total. We have to select 4 out of them which can be done in 6C4 ways. And from each of these classes we can select in 2 ways so 2^4.
So totally there would be (6C4)*(2^4) ways which comes out to be 240 ways.
Second logic
There are 12 members to choose from which can be done in 12C1 ways. Then for the second spot, we have 10 members(we can't choose the guy already chosen plus the guy in his class). third spot can be filled in 8C1 ways. Fourth spot can be filled in 6C1 ways. SO this can be done in 12C1*10C1*8C1*6C1 = 5760. 
The answers are starkingly different but I can't seem to find any flaw in both the logics.

The question was poorly formulated.  The intention was presumably to ask how many possible subcommittees there are, and then the first answer is right. But I think one could understand "ways ... subcommittee ... be formed" to refer not to the result (the subcommittee) but the process of forming it, and one could imagine that this involves choosing members sequentially.  From this point of view, the "formation process" that chooses Leonardo, then Donatello, then Michelangelo, and then Rafaello is different from the process that chooses Michelangelo, then Donatello, then Rafaello, and then Leonardo, even though the resulting subcommittee is the same in both cases. Under this interpretation of the question, the second answer is right.
Note that each possible subcommittee has 24 possible orders of formation, so the second answer is 24 times the first.
