Probably, though I suspect not enough to make any real-world difference. Seems intuitive that a Grip, 530, or even 940 would be a bit weaker than, say, a 610 or 520. But I guess I'm mostly just basing that on how they "feel"; I suspect we'll never get an actual answer to this.
That said, the "strength" of the lock (that is, the physical toughness of the components, how much force can be applied to the blade before the lock collapses, etc.) is hardly ever going to be the determining factor in the reliability of any quality modern knife. Rather, things like how you're using the knife, accidental unlocking of the blade, and factory defects will be much more important to consider, since you'd be MUCH more likely to encounter them than you would be to exceed the maximum force a lock can handle.
Let me put it this way: I'd be afraid of breaking the blade or handle (including pivot, liners, a screw here or there) of a knife before its lock. And as far as that goes, I'd trust the Rukus a bit more than the Grip, since it's got a full, beefier liner, no plastic, etc.