Bob F. wrote:

The acronyms speak for themselves:

One refers to rules, the other to conditions:

IMC - Instrument Meteorological Conditions - Condition under which
flight instruments are used to maintain control of an aircraft. How
used: "Flight into IMC". One would not say "an IMC rating". If you
can use outside references to maintain flight you are not in IMC... as
in "flying in and out of IMC".
/snip/

Bob,
Where did you get that definition? The Pilot Controller Glossary states:

"Instrument Meteorological Conditions - Meteorological conditions
expressed in terms of visibility, distance from cloud,and ceiling less
than the minima specified for visual meteorological conditions."

Happy Flying!
Scott Skylane