Vanilla arch basically just gives you fdisk/gptdisk and lets you use it to create the partitions you want manually, and then format them yourself, and then mount them. It does provide a script so that once you've done that it'll install the core packages to that and copy across various configuration files you've already touched, and write your initial fstab based on what you have mounted currently which is neat. But then you have to write your MBR/VBR or do what you need to do to make gpt discs bootable and if you balls that up you'll need to boot off your install medium again, reconnect to the internet, set your keymap, maybe mount your discs and try again, which can be a puzzle the first time you do it at least.
