I want to know the proper way of installing TWRP because recently I spent quite a lot of time bricking/unbricking my phones after flashing the ROMs, so I don't want spend it again. While learning the TWRP features I figured out two different ways of installing the TWRP:

So far I found many useful articles explaining ramdisk way of TWRP installation
https://www.xda-developers.com/how-to-install-twrp/
also quite a lot of beutiful questions/answers posted here on Android SE
Install TWRP to only one slot or offline boot.img file, not both
Why can't I write to recovery using fastboot on A/B device?
Can't flash custom TWRP recovery image on Motorola Moto G7 Power phone

Having read all that, I have a general understanding that newer A/B devices have no separate recovery partition where TWRP can be installed, so instead recovery is put onto the boot partition in some ramdisk section, or this is how I understood. Practically that means that one need to have recovery .zip or .img file in hand, and push that file onto the device to be able to install it on ramdisk. As opposed, with Flash current TWRP we don't need any files, we just make the currently booted TWRP persistent, and bootable on next and subsequent boots.

The question is: are those two options have equivalent result? If so why we have them both in TWRP menu?

In my understanding flashing the current TWRP is simpler as it does not require any file copy. Am I missing something?