A regular deadlift is easier than a RDL because you also get quad power in a regular deadlift, whereas in the RDL you don't. Even though the RDL has a shorter ROM and also has a eccentric period of amortization (that should potentiate you a bit). At least that's how I feel.
Although deadlift strength might be masked by weak forarms/upperback for some people, I think it's safe to assume they'd be deadlifting more than they are squatting if they were to use straps for the deadlifts (thus being able to express their actual strength in the deadlift)