print design - How do Pantone coated and uncoated colors relate?

I need some help understanding the relationship between coated and uncoated Pantone colors.

From what I've read online, the coated formula (say 200 C) is for printing on coated (glossy) stock, and the uncoated variant (200 U) is for uncoated (non-glossy) stock.

This would lead me to believe that the colors are formulated to look as similar as possible when printed on their respective stocks.

However, they look quite different on my display, and when running them through the Pantone xref app targeting the TPX color book, it returns rather different results for each:

200 C => 19-1763 TPX
200 U => 17-1641 TPX

Is the difference between colors achievable on coated and uncoated stock severe enough to lead to this discrepancy? Or am I mistaken about the coated and uncoated colors being meant to produce the same results on their respective stocks?

When a color is referenced as simply Pantone 200, should this be construed to meant the coated or uncoated color?

Answer

You're pretty much spot on, they are formulated differently for the different papers. Uncoated is a more matte finish whereas coated is for glossier finishes, although in part that is down to coated paper being naturally more glossy. Additionally due to the lack of the steaming and pressing process, uncoated stock is by far more absorbent and requires the inks to be thinner and in lower quantities, however, in the vast majority of cases, the result will be almost identical. Its important to note that uncoated will obviously bleed more, by a margin of up to 10% extra, causing a shift in the print, especially with halftone printing, which will in turn affect the visible output.

In recent years however Pantone have skipped the U/C variants for the consumer market, and by default target uncoated variants. Some colours will look drastically different due to the difference in absorbency and whiteness of the paper, due to pantone white actually being transparent, to let the paper's whiteness show through.

In short, by default uncoated will be targeted, but if in doubt, contact your printers.