dave2008
Legend
The CRs are designed to be "tougher." Like Fifth Edition Foes. It hews closer to the DMG guidelines than the MM, and rounds fractions down on CRs.
I will dispute the bold part. I haven't check ToB hardly at all, but the Iron Ghoul mentioned checks in at CR 7.5 per the DMG vs. CR 5 in ToB. I have checked a lot of monsters in the MM and they tend to be spot on. Even the more complex higher CR monsters I posted about in post #16 only had a maximum variance of 1.
Now, that doesn't mean that the ToB monsters are closer based on the encounter guidelines, but they are not closer to the DMG (at least in the 2 examples in the OP)