As a non-American, I’m very confused by this. If it’s a town, it’s not rural by definition. Because, you-know, it’s urban.
Also, could we get a definition of town vs small town. Do you not have the concept of a village? (Village in the UK would be a settlement with a population of a couple of thousand, with usually a pub, local shop, maybe a post office and primary school if you’re lucky).
All these fancy answers and I’ll give you a real simple one: sidewalks and paved roads. Does it have fully paved roads and sidewalks? Urban. Does it have that and mostly houses? Suburban. Some/no sidewalks and the roads aren’t all paved or is done poorly? Small town/rural. It’s all about the concrete/asphalt to dirt ratio.