And yes they are equally hard, because lunar Dragon is manned - Red Dragon wasn't, but distance was much greater.
I'm not sure about that; Red Dragon would have deviated considerably from the Dragon 2 capsule -
With Lunar Dragon, they're taking a capsule that they've already been working on for years to accommodate a human crew
Your comments are similar to comments I've seen over the years when people try to characterize what SpaceX is doing, but I think they're overly simplistic.
The gist of the argument seems to go like this: SpaceX is already building a crewed vehicle that can do X, Y and Z, so adapting it to do A, B, or C is "relatively easy."
I've seen people make that argument about the original Dragon cargo capsule, for instance, claiming that it was already pressurized, already had rendezvous and docking equipment and other stuff, and really "only" needed to test an escape system and then it would be ready to carry crew. Except that SpaceX later announced that they would have to do some substantial updates--pretty much developing a new spacecraft--to meet the crew launch requirements.
I saw people make the same argument about Dragon with regards to sending humans (not simply an empty cargo hold) to Mars. People claimed that Dragon with the SuperDracos "already" had that capability.
(As an aside, I also saw people make the same claim about Falcon Heavy--that since it was "simply" three Falcon 9's bolted together, it would be easy to do.)
And now you're pretty much making the same argument regarding this circumlunar mission, that it is relatively straightforward because they've already got most of it done. (Except that they have never launched anything out that far, an operational capability that they might want to demonstrate robotically before doing it with humans.)
Several of these claims have already been essentially disproven by experience: if these things were as easy and straightforward to do as outsiders claimed, then why the delays? Why was Falcon Heavy promised in 2013 and not flown yet? Why hasn't a crewed Dragon flown yet? Why is RD delayed? I think the answer to all of these questions is that none of this stuff is as simple and straightforward as the outsiders claim. The hardware for each of these missions has to be specialized and that takes time to do. Couple that with the fact that SpaceX already has a pretty full plate, with trying to recover from the accidents, trying to launch a backlog of commercial customers, trying to get reusability for their first stage up and running, trying to develop new launch sites, and trying to develop the crewed Dragon. That's a lot of stuff to do and adding on things like Red Dragon and now this circumlunar mission is probably straining their capacity.
I'm not dissing SpaceX. I'm pointing out that claims that their existing hardware can "easily" be stretched to do things that it was not originally designed to do are inaccurate. They have to invest in those new things and build in the capability, and that takes people hours and money.