Please stop posting pictures of autistic people (especially Greta) with a photoshopped flag looking like the Nazi flag.
This is slightly out-of-topic, but:
there’s a weird dude in my country, being both an eugenicist and a climate denier, claiming to be "anti-Greta Thunberg" (in his literal Twitter biography). (The dude’s life is so empty he’s campaigning against a 16-years-old girl, but he’s still writing in major media outlets.)
The literal US President said she was an angry kid who should chill with a friend of her. She’s written it in her Twitter bio (because look, she’s literally tougher than the US President).
I’m writing this here because there’s a good BO, so I assume you’re slightly more educated than the average 4chan user. Please don’t prove me wrong.
Now, to answer to the OP:
There are four major differences between Qubes OS and OpenBSD.
1) Qubes OS runs with Linux as its kernel, which makes it faster than OpenBSD.
2) Qubes OS is a desktop OS, while OpenBSD can be used for servers, firewalls, etc.
3) Qubes OS will guide you to use it safely, while you need to read MWL’s Absolute OpenBSD to correctly use OpenBSD.
4) Qubes OS is full of competent contributors devoted to help you to safely use OpenBSD, while the OpenBSD contributors don’t care that you use it: they target OpenBSD for themselves; you’re free to use it for your personal use or as a base for your server’s operating system, but not to ask the devs to debug your installation, unless you’ve narrowed your answer and provided meaningful logs (Absolute OpenBSD, chapter 1, IIRC).
1) Qubes OS is a secure and _safe_ operating system. If you use it properly, you shouldn’t mess up.
2) OpenBSD is a security-first operating system, with poor parallelism and defaults such as "we will only use 2 cores of your CPU, to improve your installation’s security". You can make an illegal copy of an Absolute OpenBSD .epub file on the Library of Trantor (click here: http://xfmro77i3lixucja.onion/download/KwPy9zRfQ4304KPm/Absolute%20OpenBSD.epub).
TAILS is different. TAILS is for activists, to manage one’s secret identity. It’s intended to pass everything through Tor, to be hard to misuse, and it loads in your computer’s RAM so when you turn it off, there’s no trace (except in the encrypted persistent storage).
TAILS is for grassroot activists, anticapitalists, and so on, and it runs on a boum.org SLD. boum.org claim to be anticapitalist and to like Debian and GNU, so I wouldn’t praise their opinions too high, but I’d still unconditionally recommend TAILS to student movements, civic disobedience, and so on, because even if it’s not a magic bullet it would painlessly and dramatically improve their anonymity compared to Microsoft-owned, Apple-owned, and Google-owned operating systems. (The persistent storage lets users keep a single identity on their keys.)
TAILS isn’t meant to be a workstation, like Qubes OS and OpenBSD may be (and for example, you probably won’t keep your music library on a single USB key, because for the price of a 128 GB USB key you may buy a 2 TB HDD). TAILS should be used and understood as a mean of communication, whose heaviest use would be to write a document in Libreoffice.