The frequent discussion about different terms for types of transit systems points out how inconsistant the vocabulary is in North America. Usually, when you attempt to categorize things, you have to be arbitrary about some choices, but here's the vocabulary I use. I draw on the terms used by Vukan Vukic and Richard Kunz, but disagree with both of them in one way or another. Suburban stations are typically spaced more than a kilometre or two apart.
Service is typically city-centre to outlying suburbs.
Electric powered multiple-unit trains are nearly universal. Service is typically intra-urban, with stations spaced from a few city blocks to around a kilometre or two apart. BART in San Francisco comes the closest to being CR rather than HR, because of its station spacing and regional service area. Configuration is usually small vehicles operating frequently, with stations spaced close together. The Downtown People Mover in Detroit uses the same technology as SkyTrain in Vancouver and the Scarborough RT in Toronto.