I suppose that H10/H20/H30 is the generation part, and that A, G or N indicates something in them?
They would be for the engine
In the same way, the W at the end probably had a meaning.
That would be the bodystyle
But in general I'm rather in favor of generic codes, like the Jx0 codes for the Land Cruiser rather than the more specific ones that also include engine and other details.
As it is a big change, I'll wait a little in case someone wants to comment on that, or if for some reason we want to keep some difference in the names.
Sometimes we get a little too specific, but some like to be very precise. For Toyotas, I usually don't mind, especially with the Land Cruisers that come in different wheelbases and bodystyles. The more specific code can make it easier to find specific models when searching.