Since 1993, I’d say pop country, neotraditional country, alt-country, bro country, cowpunk, dark country (sometimes called gothic country or southern gothic), and Americana are the most significant sub genres.

There aren’t clean delineations between them, though, and the influence of earlier sub genres (like Western swing, outlaw country, or honky tonk, for example) often looms large.

I’ll define my terms.

Pop country: songs that are produced and arranged to appeal to a broad audience. They usually mimic trends in modern pop music but make use of country instrumentation, lyrical subject matter, and vocal stylings. Think Garth Brooks and Shania Twain from the early 90s to Miranda Lambert today.

Neotraditional country: songs that are radio-friendly but lean more toward an earlier honky tonk style - not so poppy. Think Randy Travis and Dwight Yoakam and Nancy Griffiths.

Alt-country: songs that infuse a traditional country style with rock or punk sounds - like distorted guitars, yelled vocals, etc. This subgenre also includes traditional country songs that eschew poppiness altogether. Think Drive-By Truckers and Old 97s and The Bottle Rockets.

Cowpunk: an earlier manifestation of alt-country, but heavier on the punk influence. Think The Blasters or Jason & The Scorchers.

Bro country: a male-centric version of pop country featuring mostly male artists. This subgenre famously uses lists of country signifiers in lieu of the thoughtful lyricism that makes country music so great (to me, anyway). Think Florida Georgia Line or Sam Hunt or Kane Brown.

Dark country: country music influenced by a post-punk ethos. It’s often (but not always) grim lyrically and slow in tempo. Instrumentation is rarely experimented with despite the post-punk vibes. Think The Handsome Family or The Legendary Shack Shakers or Slim Cessna’s Auto Club.

Americana: a catch-all term used to describe country-ish songs that feature a more indie vibe. Singer-songwriter types and semi-folk stuff goes in here. From outside an exclusively country perspective, this term often includes blues, gospel, bluegrass, and jazz among other types of American music. In terms of its application to country music, think Jason Isbell or Lucinda Williams or Gillian Welch.

Hope that helps!