It compares primarily the biggest elements of each suite, the ones which users are most impacted by. That includes the interface, styles and page layout, included templates, page formatting and a lot more. The curious thing is how many categories the author preferred OpenOffice in. Bias aside, it makes me want to actually try the two writers side by side. Word processing is something really taken for granted these days, and OpenOffice has matured enough that it wouldn't surprise me if entire companies began “switching”.
Comparisons between Office suites are sometimes moot – someone who is using a particular program is unlikely to change. Some of us may never try another program. That's why actual comparisons, when done right, are fun to read.