I always believe that the usage of so and too is different from each other:
He is so busy until he is able to forget his problems. (=+ve sense)
and another one
He is too busy until he does not have time to eat.(-ve sense)
Consider the following sentence:
i)This place is so hot.
ii)No wonder, the shirt's so big.
How about the sentences above?
Is it grammatically permitted to use them interchangeably?