Many softwoods look similar to the naked eye at first; the colors are often similar, maybe light-colored overlaid with tinges of yellow-brown or perhaps a slight pinkish cast. Even the weights of similarly-sized pieces (the densities) might seem similar. There are, however, differences in the wood structure that we can use to separate the various species. Two of the most important characteristics we look at are 1) the presence or absence of resin canals (as discussed previously) and 2) the appearance of the earlywood--latewood transition in annual growth rings.