Apologies for listing the Selke. Not sure where I got that from.
They have similar production. Pav played 173 less games. think that's a pretty significant difference and that's not even taking into account the defensive side of things. You say they both had 2 90+ seasons, but Pav also had 2 80+ seasons as well while Richard does not.
And, yes, Richard had a decent defensive game, but not on the level of Datsyuk. Richard's highest +/- was +13 (with a cup winning team). Richards was only a plus player 6 of his 17 years. He played on some bad teams, but not that much. Datsyuk's highest +/- was +41 and was only not a plus player 1 year (2nd year). And I know that +/- is partially a team stat, but surely +249 vs -67 for their respective careers at least says something their difference.
You can look at many more reliable stats to show Pav's superior 2 way game, though:
Takeaways: 345 754
Giveaways: 424 380
Face-Off%: 50.3 54.8
Hits: 207 512
Corsi%: 51.7% 59% (since 07 when they started recording these)
Fenwick%: 48% 58.2%
For a while Datsyuk was considered the best all-around player. That was kind of the common line amongst commentators that I remember for a while.
That last line is the separating factor for me between Datsyuk and Richards. It seemed like a pretty common thought thay Datsyuk was the best all around player for a few seasons there.