Its a different type of gold deposit from what ARU has. ARU is exploring an Epithermal deposit (related to volcanic activity). KXL is exploring an Archean Shear deposit (formed by pressure and shifting plates in the earth and fault lines etc).

Although 3-4 metres may not sound very glamourous the tonnage can add up very quickly if the strick length is long and high grade. Plus there may be a significant number of similar veins as they drill deeper since Archean-Shear structures generally go down for a few KMs.
KXL has already begun to prove such a deposit and looks as though they could have many more like it on their land as well.
I would suggest reading up on Gold Corp's Red Lake property. They have very similar geology to Hercules and are well into the millions of ounces.
Hope that helps somewhat.
Cheers.
Gamblor.