You need to familiarise yourself with the independent chip model (ICM).
You can't use chipEV diff to evaluate tournament play. Basically put, in cash games each chip has a monetary value that is constant forever; you can (in theory) buy-in or cash-out your chips at any time. In tournament play only a set amount of players will win any money at the end therefore the monetary value of each chip changes through the tournament. All this means that in cash games a +chipEV play is always +$EV but in tournaments a +chipEV could actually be a -$EV play (i.e lose you money in the long run).
Very simply this explains why for tournaments you should look at the 'ICM diff' or '$EV diff' stat (in HM2, I don't know in PT4). There are plenty of free articles out there explaining chip
expected value, dollar expected value and the independent chip model in much more detail and far better than I can - I recommend you get reading!