Parts per million (ppm) and grams per tonne (g/t) are the same thing. g/t is normally used only for precious metals, i.e. Au, Ag and PGE's, whereas ppm can be used for anything. In base metal exploration, results will normally be quoted in ppm, until they get to a level where they make sense in percent. Ni, Cu, Pb, Zn assays over 10,000ppm will normally be reported in percent, but you might see a mixture of ppm and percent assays quoted (eg 0.5% Ni or 5000ppm Ni).
Au and PGE's will normally be reported in ppb (parts per billion where 1000ppb = 1ppm or 1g/t) or g/t when the numbers get to that level. There's nothing wrong with the way the results have been reported in the OP, that's the convention.
