RTM (Release To Manufacturing) is a term reserved for the first official public release.
GA (General Availability) is an alternate term for the first release, but sometimes it might be one month later than RTM (as the first patch update).
Both are fixed milestones, even if there are later versions of the same Windows.
Windows can be provided as ISO files, or downloaded as ESD images (via Media Creation Tool). Media Creation Tool will convert the ESD into ISO format for you. ISO's and ESD's do not have to match in build versions, and frequently don't.
You can use the term the current "servicing level" for 23H2, as 22631.4169. Servicing level is a synonym for patch level. The build number increments every time a Monthly CU or Monthly Preview CU is released.
For retail customers, MS does not constantly re-release the ISO or ESD. You're expected to download the last available one, and run Windows Update to bring it up to the latest patch level. Whether you have .194 or .318, it will be updated. The only time the ISO version matters is if you're one of those people who insist on never updating their Windows, and actively block Windows Update from doing its job.