Endeavour is Arch with an easy to use graphical installer and a few changed defaults. IMHO it should be merged into Arch itself as an installer option, but I guess making it too easy to install is against the project philosophy… It’s basically Arch aside from those details.
Manjaro uses the Arch packages so it’s also rolling (not sure what the other comment means saying it’s not) but curates everything heavily. It has a “stable” package branch which doesn’t exist on Arch, where packages enter after testing and a two week delay on average (probably where the rolling confusion originates from; it’s still rolling, just later).
It comes with a LTS kernel by default and all kinds of other safety and helpers. It has its own package manager with a GUI, a driver detection and installer, a kernel version manager, automatic OS snapshots after every upgrade so you can restore if something breaks etc. (I’ve never had to use the restore but it’s nice knowing it’s there I guess.)
It’s quite stable and nice (I’ve been using it as my main desktop driver for work and gaming for the last 4 years) but you have to stick to its recommended features for it to remain stable. There are people who switch to the non-stable branches, or use non-LTS kernels or do other changes and it breaks and they end up upset.
There are all kinds of rumors circulating about it because of that, saying you can’t use AUR packages on it (you can) or that it’s buggy, “badly managed” etc. From my own experience it’s a perfectly nice distro provided you want to get the distro out of the way and focus on doing other things, but still take advantage of rolling packages. If you want to experiment and tinker with the OS you’re better off on Arch or installing through Endeavour.
Garuda is somewhere in the middle, has an installer and nice defaults like Endeavour, has helper GUIs like Manjaro and uses Manjaro’s GUI package manager, but doesn’t take things as far as Manjaro (with the stable branch and kernel and curation etc.) Also has a gamer-oriented thing going with a cool desktop theme and a gaming package manager GUI.