Aircore = exploration, cheap, fast, drill chips blown back to...

Aircore = exploration, cheap, fast, drill chips blown back to surface through inner tube (which is an important point as with similar RAB drilling chips are blown back outside of rods = high rate of contamination and smearing compared to AC), penetration is limited to pretty much regolith only (weathered profile). Diamond drilling = high cost, slow, deep penetration into fresh rock, important for determining structural details and ground conditions. You should def google drilling for more in depth details.