From the pictures, I agree, it's hard to tell. Some of the smaller rounds have distinctively red heart wood but the bark is more consistent with white. This may not help determine the variety but I looked up the difference in my Dirr book: White oak bark on old trunks is light, ashy gray often broken into small, vertically arranged blocks and scales. Older trees have deep fissures with narrow ridges; sometimes with rather smooth, gray spots.
Red oak bark on old trunks is brown to nearly black and broken up into wide, flat-topped, gray ridges separated by shallow fissures. On very old trees the bark is often deeply ridged and furrowed.