I'm not familiar with elk nut, but at a quick glance it looks like it's mostly focused on calling. It's only $10 so not much risk if it's not valuable to you.
Elk101 has a chapter on calling but is much, much more. Corey has done a damn fine job of turning his strategies and experience into a learn-able format. It definitely changed the way i approach hunting and i believe i owe a lot of my success to the course. The only negative i can find is that if you watch enough OYOA and listen to the elktalk podcast you'll receive much of the same info for free. If you've got 20 years of success under your belt you probably don't need it, but if you're a newer hunter or don't always get into the animals you know are there, i'd HIGHLY recommend it.
I had a membership to Elk101 a couple of years ago and own the Elknut app. They are VERY different tools. Elk101 has everything under the sun when it comes to elk hunting (applications strategy, e-scouting, gear, hunting tactics, set up, elk behaviors...) where the Elknut app is about Paul Medel's interpretation of elk language (which has proven successful for a lot of people, but others feel that its a bunch of crap). Corey has said many times that he feels that calling elk is more about "feeling" than trying to understand if each elk sound has an exact meaning where Medel feels strongly that they do. Both seem to have a lot of success and have loyal followers. Hope that helps.
I have had both and also had the Roe Hunting Resources membership app at one point. All were good info in my opinion but I definitely prefer Corey’s methods and the elk 101 app. It’s easier and much more straightforward. I feel it has helped me significantly
Im a big fan of Paul “The Elknut”. Really nice guy and his info is great. He is a very passionate elk hunter to say the least! I studied paul’s tactics for a couple months prior to my first elk hunt. My brother and I killed two mature bulls in 4 days of elk hunting using Paul’s tactics. I highly recommend listening to some of the podcasts he has done. I think listening to Paul and understanding his tactics in conjunction with using the app are valuable tools.
Several podcasts cover pretty much the same info as UEH. Had it for 2 years and haven’t renewed.
I listen to Paul’s app everywhere all the time. Definitely worth the $10!
Paul adds to the app from time to time, not so much with UEH.
Like above, I have both and like both for two different viewpoints. For the $10 I can't see not getting the app if you are at all interested. It comes with tons of recorded calls and explanations of why the elk is doing that and how to use that to your advantage which is worth the $10 right there.
Elk 101 is great, I learned a bunch there as well.