Irvin was by far the more physical of the two despite Terrell's build. Irvin just bullied DB's ... they dreaded playing against him because they knew they were going to war. Owens however is certainly the better deep threat because of his speed.
As far as some of the other posts about who was more dominant, the Cowboys win zero Superbowls w/o 88. He had the intangible ability of being the ignition switch for his team giving them a united focus and "swagger" if you will. Whenever 88 showed his flare on a football field the result was a "team" igniter and uniter, he was a team leader in every aspect on the football field. Owen's has been the anti-Irvin in regard to these intangibles to this point, and it directly affects his and his team's dominance on the football field.