These slight discrepancies in classifications between systems do have occassional canon implications. I think the key is to remember that in any system the trade classifications are very broad and not absolute. You could have a world that meets all the Scout Service requirements for a garden world but is tide-locked to an M5V primary and the twilight zone is not at all garden-like; you could have a "technically" agricultural world with a Tundra climate that isn't able to grow much beyond wooly mammoths.
I once tried to wrap my mind about the Ga (Garden world) code. As far as I can tell, it refers to a world along Terrestrial Earth-like conditions, meaning an agricultural (Ag) world with a temperate (Tp) climate, not tropical or tundra, cold environments. In other words, it is a world capable of sustaining homo sapiens under relatively comfortable conditions with abundant temperate climate crops such as life-sustaining grains, vegetables, and fruits. And where those plant products exist, so can corresponding livestock animal foodstuffs...
Certainly, agricultural (Ag) worlds could appear with different climates.
Early Traveller sometimes called them Terra Prime worlds...
But, I'm certainly no expert... I would go to Rob, Aramis, Jim, or Thomas for one of those...
Shalom,
Maksim-Smelchak.