Chalky Vs. Chalk Surfaced Paper

Am I right in thinking that there's a difference? And that this is it?

Chalky Paper: Older stamps were occasionally printed on paper treated with a chalk solution. The paper, that is, was first treated and the ink then applied on top of that chalky substance. Thus, the ink did not sink into the paper fibers. This was done to prevent cleaning and reuse of stamps: a promising idea, insofar as contact with any cleaning solution, including water, would wash off the ink. In practice the ink was usually just compromised, leaving the stamp looking severely faded or badly discolored. In addition, some countries, e.g., Russia, treated paper with chalk in an effort to prevent stamps from curling, a common problem with the early use of gum.

Chalk Surfaced Paper: Modern stamps are often treated with a chalk or clay substance, not in order to prevent reuse or curling, but to produce a clean and shiny appearance. In this case, the ink is first applied to the paper; the chalk is applied afterward, i.e., on top of the ink. Soaking may affect the shininess, but not the ink.

Please correct me if this is inaccurate or simply plain wrong.

I think they are one and the the same. There are degrees of application, with (say) Russian stamps having a thinner coating and Commonwealth stamps a thicker coating. If Russia intended that the surface was to be fugitive, then they failed completely over many years; there are too many stamps that came through a soak in fine shape. In both of those cases, part of the idea was to try to prevent reuse by cancel removal.

I think you're right. I've checked a number of references, and nearly all treat the terms as equivalent. The only exception is Stanley Gibbons, Philatelic Terms Illustrated (Mackay, 1987), which says that Chalk-Surfaced Paper was introduced by De La Rue in 1902 and used for many of its letterpress (typographed) stamps, whereas Chalky Paper is a term "more properly applied to the whiter paper introduced to British stamps in 1962 to improve their appearance." That means my OP got the definitions exactly reversed, but also that there really isn't much need to worry about the difference.

All sources do issue dire warnings against soaking chalky or chalk-surfaced paper. It was used mostly to prevent cleaning and reuse of stamps, and moisture is supposed to compromise the ink or even wash it off entirely. Again, however, you're right to observe that in practice this doesn't seem to happen. Most of my chalky paper stamps are used and in good shape, though clearly someone soaked them. My thesis now is that, while soaking is probably fine, any effort to remove the cancellation would, because of the chalk surfacing, destroy the image.