when timed correctly, tnt will destroy more blocks as in java. but those blocks will not drop.
this doesn't happen all the time.

testing setup
1. place a 7x7x12 area with pistons pushing from the top.
2. tnt is lit, dropped after a 28 redstone tick delay.
3. 13 redstone tick delay before it pushes the blocks.

results are not constant enough to tell rate at which this happens, but most area will be destroyed without dropping the blocks, other times will only effect a 5x5x5 area where the block will drop