While some bodybuilders are incredibly strong, they train differently than strongmen do in a lot of ways. The most obvious thing is that bodybuilders do more reps (further away from a 1 rep max) and do more exercises for smaller bodyparts like biceps/triceps/shoulders/calves/etc.

Sure, there are a few (very few) bodybuilders that can deadlift 700lbs (with straps, belts, and whatever else) but strongmen regularly deadlift much much more than that. I think the record is close to 1100 lbs.