no difference in the figures.
thr RTG-Pack is just an extra bunch of turtles.
The only difference is 1 or 2 cards, that are exclusive to the pack.
So to have *all* the relics/loot 1 you'd have to buy 1 box. But I don't think 1 extra treasure card is that important.
And from a financial standpoint 2 CoR boxes are more worth than CoR+Turles+Flamecreatures.