I feel that it is wrong to conflate "ground source heat pump" with "geothermal".

Ground source heat pumps use the soil or ground water as a low temperature mass to draw heat from. Surface soil follows air temperature, with a lag because of its high thermal mass. Below a meter or so this lag becomes so large that it just stays at the annual average of the air temperature. So the heat is not coming from the earth below!

I would reserve the word "geothermal" for projects that actually access high temperature sources, where the heat does actually "come from below".