The NBA title is the hardest title in Major sports to win.

No I didn't say that, but the OP of the thread said that NBA playoffs are the toughest because they must win 16 games over 2 months... which is exactly the same as hockey.

But whether you like hockey or not you have to admit hockey is a MUCH more physical sport, so hockey playoffs = MUCH tougher.

On that definition, yes, but I think the OP was using 'tougher' as in 'the probability is lower' and not as 'its physically tougher'....in which case, I still have to go with the Champions League. When the NHL or NBA has to play multiple leagues, three to five of which could be argued to have equal quality in talent, then it may be up for debate.