This whole what regions and boundaries of those regions are so blurry here in central Texas because of the many layers of governments and quasi-governmental organizations, historic land use patterns, and overlayed decades of infill and redevelopment, that any attempt is going to be rife with personal bias (as is mine).
These images represent, to me, what are the broad strokes regions of non-farm non-rural commerce in and around Austin.
In the center, you have a color wheel of urban and suburban Austin and other centrally located jurisdictions. The closer in color are two areas, the more similar they are. Around them, in shades of brown, are the major suburbs or unincorporated development areas that have lately porous development boundaries with the city of Austin itself (I.E. together these two groups are roughly the “urban area”, though I am slightly more generous than would be the census bureau). Beyond that, in various shades of grey, are the rural communities and satellite cities and towns which surround Austin and dot Austin’s rural hinterlands. Additionally, I’ve included Austin’s primary resort and vacation towns in a selection of blues.
In all cases, darker colors represent more intense development and lighter colors both less intense and less consistent development patterns.
Also note that within the city are the primary urban clusters that rise to their own level of significant rather than simply being a commercial area situated within the broader context of a neighborhood area (think of the difference as being that SoCo is part of the broader South Austin context, but Mueller is distinct in development, history, connections, urbanity, and many other factors from East Austin). These are in shades of grey. Also, in burnt orange are the two UT areas.