Softwood and hardwood trees are made up of different types of cells. With just a little magnification, it’s easy to see that softwood growth rings look different from hardwood growth rings. Additionally, growth rings don’t look the same for all of the trees, and the growth ring appearance is one of the things we will look at to identify wood.
Conners, Terry, "Distinguishing Softwoods from Hardwoods" (2015). Agriculture and Natural Resources Publications. Paper 105.