Surface
Mold-made and machine-made watercolor papers come in three surfaces: rough, hot-pressed (HP), and cold-pressed (CP or NOT, as in "not hot-pressed").
Cold-pressed watercolor paper has a slightly textured surface, somewhere in between rough and hot-pressed paper. It is the paper used most often by watercolor artists because it is good for both large areas of wash, as well as fine detail.
from here: https://www.thoughtco.com/how-to-choose-a-watercolor-paper-2573985
I was just what I had on hand.