"Joseph Meehan" wrote:

In the traditional sense Macro is anything recorded
on the light sensitive material at life size or smaller to about half to
quarter life size. Micro is used for anything recorded larger than life
size. Those terms don't have a lot of meaning in the digital world with
the changes in sensor size, but from a technical view, I would guess they
still apply.

From "The Science of Imaging: An Introduction" by Graham
Saxby,

Photomacrography is the making of an image that is larger
than the object using conventional camera technques.

Photomicrography is te technique of imaging through a
microscope.

Generally though, macro has become more broad in meaning and is
now commonly used for 1:4 ratios on zoom lenses rather than only
at 1:1 or more.

But the basic difference is the use of a compound
microscope (micro) rather than a generic camera lense
(macro).

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)