Oak tree and White oak

Oak tree noun - A deciduous tree of the genus Quercus; has acorns and lobed leaves.

White oak and oak tree are semantically related. In some cases you can replace phrase "White oak" with "Oak tree", this phrases are similar.

White oak noun - Any of numerous Old World and American oaks having 6 to 8 stamens in each floret, acorns that mature in one year and leaf veins that never extend beyond the margin of the leaf.

Oak tree and white oak are semantically related. You can use "Oak tree" instead a noun phrase "White oak".