I found a couple vm.
What are diffrents and which one is simple?
Simplest, probably virtualbox. It has the advantage of being compatible in Windows as well, so you can transfer your "know how" between both OS. Of course that also means that you can take snapshots from one and use on the other (I think, never actually tried this).
On the other hand KVM is Linux-specific and has much better performance. You can also configure it to take advantage of the hardware in runs on which means you can create a VM running Windows and still take advantage of an external video card.
I haven't used Proxmox or VMWare so I can't really speak to them.
I saw many poeple using vm to creating linux.
So then creating linux i need some linux live. From them I need creating a host then prepare pendrive and save there package and another some stuff like boot,kernel and packages.
Not sure I understand, are you trying to run some Linux distribution inside a virtual machine? If so, all you need is the .iso file that you can download from the distribution's site.
For something more advanced like creating your own image, I have no idea how to go about doing that
Yes. I want learning how it works from Linux From Scratch.
VMware ESXi is a bare-metal hypervisor, meaning it's a complete OS. You will need one computer for ESXi, and another for controlling it. And the hardware requirements are quite strict - it's meant for servers only basically.
VMware workstation is probably what you should be looking at.
Virtual box would be your best to test new distros and a virtual environment if you don't have a test PC to use real hardware
I know some software ventoy where you can installing many distribution on one pendrive.
Yes I've heard of it I prefer to use a pendrive for each distro but then again I have many pendrives just lying around and I have a distro draw of mint, Zorin, arch, and endeavour OSes
I actually still think I have my Gentoo somewhere too
I had some major issues with Ventoy as it uses Ex-FAT - I scrubbed it and went back to my trusty MultiSystem stick - won't run recent releases but will run some others.
Gentoo isn't that from Ubuntu? Gentoo can LFS.
Gentoo is an independent distro like arch but you compile everything yourself so essentially you are also building the packages from scratch on each install and update
Top 10 Best Gentoo Linux Derivatives To Explore - just because it is on ubuntupit does not mean it is an ubuntu derivative as justinc has pointed out. Gentoo/Sabayon frown on 'sudoers'!
Something like writing a new book.
The analogy could be used, yes.