Compared to spruce, Douglas fir is:

Douglas fir is indeed stronger than spruce, making it a preferred choice in many aviation applications, particularly in structural components that require high strength-to-weight ratios. The wood of Douglas fir is known for its density and stiffness, contributing to its overall strength. However, this strength can also make it more challenging to work with compared to spruce, which is generally softer and more pliable.

Working with Douglas fir often requires specialized tools and techniques, particularly in cutting and shaping, as its dense fibers can lead to increased wear on tools and might necessitate more effort to achieve a smooth finish. Spruce, being lighter and easier to manipulate, does not pose the same challenges, making it more user-friendly for various woodworking projects.

The comparison to spruce highlighting the quality of strength in Douglas fir, alongside the difficulty in handling it, results in the correct understanding of their differences. Other options do not accurately capture these material properties, such as resistance to insects, which is more related to treatment and environmental factors than a straightforward comparison of species.