Good question. I'm probably going to blog about this at my blog site to go into more detail.
But in summary it's quite a similar idea. Certainly we are looking at solving much the same problem.
In the main I'd say the difference is in build vs buy and to a significant degree that shows a difference in philosophy. My project is trying to build something and give users choices and options. Helm is the buy a device and let someone else have done all the hard work.
The problem with the helm approach is that you are reliant on helm. If you buy a helm device and it doesn't work you have to get another one from them. Helm appears to be somewhat closed and proprietary in terms of OS and hardware. My project is based on Raspberry Pis and there are numerous suppliers/resellers of pis, however nothing in my project requires even a pi. It would be very simple to port this to an Intel/AMD CPU platform like a NUC. The Helm project mandates using helm's cloud for backup and various other things. Mine has no such dependency. You get a domain from any registrar and so on. Yes it uses cloudflare now but there's nothing that requires cloudflare, it can be moved to a different service like ngrok if/when cloudflare decides to change its offerings. One of my intended near future developments (and by near future I mean in the next week or so) is the ability to have a second pi as an offsite backup (or more than one if you are that paranoid) that you can have a friend put on their network. Unlike helm this remote pi remains under the control of you and your friend so your data isn't exposed to anyone's cloud.
With my approach you are not reliant on anyone. My project is a binding together of a variety of existing open-source software/tools and the expectation is that the user has to get exposed to some linux sysadmin concepts. That's another intentional difference because I think people should be able to tinker and that they should do some maintenance etc. themselves. Rather like the ability to change a tire, check the battery etc. in a car. Come to think of it another related difference is the use of containers, which helm touts as a feature. Although one of my applications (the chat server) uses a snap and I recommend building the project using a docker instance, the core functionality (blog, comments and future file storage) do not use snaps or dockers or other containers and the reason is that these containers are hard to look inside of and hard to be sure that someone hasn't installed something you didn't want in them.