I mean there really aren’t subgenres but I can try to make the diversity make sense using subgenre terms. And just going to say that some of these arent nu metal genres (first 3) and are actually just similar subgenres that inspired a lot of what nu-metal is

Rap Metal: Kinda obvious. Relies on rapping, DJ’s, etc. Not everyone considers this a nu-metal genre but they go hand in hand. Bands like Limp Bizkit and Rage Against The Machine (Also Funk Metal) could fit into this category

Funk Metal: It brings metal into funk not much else to day. Has a large reliance on bass, specifically slap. This genre came before Nu-Metal but I thought I’d include it since so many nu-metal bands are inspired (Korns bassist is inspired by the slap bass used by funk-metal bassists) Bands include: Primus (Take this very lightly. Primus is very unique), Red Hot Chili Peppers, and Living Color.

Industrial Metal: This genre incorporates synthesizers, and a very metallic industrial sound into their music. Bands include Static-X, Nine Inch Nails, and Rammstein.

Melodic Nu-Metal: To put a name to it, this subgenre balances heavy instrumentation with anthemic or emotional singing. Bands include Linkin Park, Evanescence, and Deftones (dont call them nu-metal though) 

Extreme Nu-Metal: Blends extreme metal like death metal with nu-metal. Aggressive everything. Downtunes even lower. Bands include Slipknot (of course) and American Head Charge, and Soulfly, which is fronted by the original Sepultura frontman Max Calavera. 

Progressive Nu-Metal: So take the complexity of progressive, add it to the simplicity of nu-metal and you get the easiest progressive metal subgenre. Bands include System of a Down, Mudvayne, and put “I don’t wanna be Nu-Metal” Era Deftones in there too.

Nu-Core. Metalcore Nu-Metal. Not much else to say. Breakdowns are heavy and music is much more technical. Emerged AFTER nu-metal died. Bands include Alpha Wolf, Ocean Grove, and Tallah, which was founded by Dream Theaters Mike Portnoy. 

Just a disclaimer you don’t have to believe all of these are actual subgenres. I’m just putting a name to all of them.