The claim that the Word layout engine is as good as TeX's is not correct.

Even for math-free text, TeX does a better job of hyphenating and line-breaking. The TeX algorithm specifically tries have low variability in line-to-line fill density. Word does not care, which can result in a loose line between two tight lines, causing horizontal stripes in a block of text.

For much more, including ligatures, kerning, and transparency, see:

http://nitens.org/taraborelli/latex

My point above is his point #7.