Humidity is one difference that comes to mind.

In most of Texas, the air outside is humid, you need a moisture barrier between your structural wall and your rainscreen/siding.

In Calgary, cold winters will have very dry air, so the humidity will be much higher inside the house. So the moisture barrier needs to be on the other side.

In either case, you don't want the insulation layer or the structural layer to be collecting condensation from the humidity / temperature differential, or you will get mold.

Disclaimer: not a builder, just deal with humid climate.

Right but "put that plastic thingy on one or the other side" isn't exactly something needing whole new plans for a house

Vapor barriers are not in any house design. They are something you put on and the inspector will check, but they are not on any house design.

Snow and cold vs. sun and heat as the primary environmental issues to deal with, as a quick example.

But also humidity, local ordinances, matching the style of surrounding buildings, the relative value of land favoring single story (texas) or tall (Calgary) houses

Relative value of land and matching style is semi valid. However none of that prevents you from take a house from one area and building it in the other. In most cases local ordinances will allow it though it will cost slightly more as builders are not familiar with some details and some materials might not be readially available. However the design itself will still work if you want to.

Texas doesn't have a subarctic climate