Unconfined aquifers:
In unconfined aquifers, water has simply infiltrated from the
surface and saturated the subsurface material.
If people drill a well into an unconfined aquifer, they have to
install a pump to push water to the surface.
Confined aquifers:
Confined aquifers have layers of rock above and below it that
are not very permeable to water.
Natural pressure in the aquifer can exist; pressure which can
sometimes be enough to push water in a well above the land
surface.
No, not all confined aquifers produce artesian water, but, as this
picture of an artesian well in Georgia, USA shows, artesian
pressure can force water to the surface with great pressure