The only thing I can think of is one of you inadvertently chose a reformulated version under the Pantone Bridge or Pantone Goe system. Illustrator supplies the Pantone libraries, but they be older versions of updated versions via Pantone.com.
The CMYK numbers depend on the CMYK color space.
Of course, the spot modifications by Pantone are confusing
That may be the case in PS, but, so I thought, Illustrator color space ( in this case ) is assumed to be CMYK. Perhaps the Illustrator color settings could influence numbers based on the .icc CMYK profile. However, I also thought that Pantone Spot Color equivalents ( percentages ) do not deviate even when color settings do not match. Maybe I'm wrong and correct me if I am, but the percentages are industry standard Pantone formulations across the board.
I thought the Pantone colors would have the same conversion also. It was in a CMYK working space. I think the original file was created in FreeHand several years ago, but that should not influence a difference in conversion values. It had always stayed in a Pantone solid coated setting. Thanks for your help.
Pantone periodically changes their recommended CMYK equivalents for spot colors, so if one of you is using an older software version that uses the older definitiions... and that's all these are, recommendations based on their printing conditions.You can often develop your own CMYK versions that are closer, especially if you are using a less-common CMYK working space.
If the goal here is to select CMYK colors for process printing (as opposed to trying to match something that is actually being printed using spot inks), it's not really a good idea to spec CMYK colors from a Pantone spot library. Much better to work from the Process swatchbook instead.
In my version of Illustrator (still CS2), I can choose for Spots:
1. Use Lab values specified by the book manufacturer
2. Use CMYK values from the manufacturers process book
In my understanding one should always choose version 1.
This guarantees a more or less correct appearance on the monitor,
if the Spots are in-gamut for the monitor - which is unfortunately
the case for perhaps only 50% of all Spots.
At least it's entirely independent of the specific CMYK space.
The print is anyway done by Spot ink, therefore correct.
I wouldn't ever choose a spot color as a design color for printing
by CMYK. Then it's much better to use a printed CMYK swatch
book for the specified process (here for instance ISOCoated V2(eci)
or something similar - definitely not a Pantone process book).
Pantone had modified the Lab values all over the years, but this
is in my opinion not a big issue. But any confusion with CMYK
will cause endless discussions.
In this swatchbook one can easily see, which spots are in-gamut
for sRGB and aRGB (AdobeRGB):
Best regards --Gernot Hoffmann