Totally different tools mate. T bar, thin, pointy, flexible. Hence the T on the top for turning to "probe".
Digging bar, maybe 4-6 ft long, several times thicker, possibly octagonal for strength, pointy ish at one end. Bang it in, twist around, lever, break up shale, etc etc.
Difference is like the diffence between an axe and a scalpel if you get my drift.
Cheers, D.