Pignut hickory (Carya glabra) here are two different winter twigs. You may notice that I originally labeled the top one as sweet pignut hickory (C. ovalis) a very similar species, so similar that many consider them the same tree. If you want to see what the twig of C. ovalis looks like look at the pictures above because it is almost identical. There is supposedly a difference between the fruits of the two species - I will post sketches of those differences soon.
Mockernut hickory (C. alba) is one of my all time favorite trees. I dont know why they changed the name of this tree from Carya tomentosa to Carya alba; tomentosa was much more fitting as everything about this tree is tometose. The leaves, twigs, buds, leaf rachis are all as furry as can be.
Shellbark hickory (Carya laciniosa) often holds its leaf rachises well into the winter, this sketch still needs some lenticels added to the twig to finish it up, but you get the idea. Another common name for this hickory is kingnut hickory and you would know why if you saw one of the baseball sized fruits. All done in colored pencil.