What is the difference between regulating and
adjusting a watch?

Regulating:
    This is simply adjusting the regulator (an adjusting
lever usually with a S slow or F fast range of setting-
see
images below
) so the watch keeps accurate time in the
position that it is in
at the time of regulation (i.e.dial up
(DU), pendant up (PU)).  A timing machine is use in order
to make adjustments rapidly. This is why the acronym
COR  (Clean, Oil, Regulate) is used as opposed to COA.
Even though the watch has be regulated, it still will run at
different rates in different positions.  The task in regulation
is to adjust it so that the
average running rate is as close to
a zero error in the most common positions. Thus, the
correct setting for the regulator will be slightly different for
each owner, depending on how the watch is worn or
carried (this is sometimes referred to
personal error). An
owner, if so inclined, may carefully nudge the regulator with
a toothpick in order to make fine adjustments. Note,
however, that the more accurate regulators are adjusted by
a threaded component, and is more difficult to adjust.  If in
doubt, let an expert adjust the regulator
(see images
below).
(Please see a complete COR checklist)
Contact me or call 530-520-1478
Adjusting:
    Adjusting a watch involves procedures that include
ensuring the balance wheel is 'balanced' (poised), adjusting
the hairspring, and even shaping the balance pivots and
adjusting how the hairspring is attached to the balance
wheel.

    The three critical adjustments are for position (as
defined above, see
accuracy), temperature (the ability to
keep good time over a range of different temperatures),
and isochronism (the ability to keep an even rate over the
life of one spring wind, typically 24 hours). An un-adjusted
watch should run reasonably constant in two to three
positions (for a pocket watch dial up, pendant up, pendant
left/right) as these are the most common positions the
watch would encounter either in the pocket, or on a table
at night.  High grade watches are adjusted to five positions
or more.

To illustrate the work involved in adjusting a high grade
watch, go to this link:
Fine Adjusting article at Timezone.com
Common Regulator
Fine adjusting regulator.  This one is moved by
turning the adjustment screw. Care must be taken
when adjusting this, as it is easy to slip an scratch
the movement, or hit the balance wheel. If you have
any reservation, contact your watch repair person.