By my understanding, rule consequentialism means choosing rules according to the utility of the expected consequences, whereas deontology argues for a duty to follow a rule for reasons which may have nothing to do with the consequences. Kant's "treat another person as an end in him/herself, not as a means to an end" doesn't mention consequences and the argument for it isn't based on assessment of consequences. Admittedly both sorts of rule may lead to the same outcome in most cases, but in totally unprecedented moral dilemmas it helps to have an idea where the rule comes from. My prejudice is that rule consequentialism is the best basis for public policy, but deontology sometimes better captures the essence of what matters in cases of private morality.