1. "Won't die" FIRE - I can couchsurf or move somewhere super cheap, eat a very basic diet, and have zero luxuries, no gym, no air travel, no restaurants. Plan on getting another job if the ACA goes away and I need costly healthcare.
2. LeanFIRE - I can live with roommates in MCOL cities, take public transit, join a gym, take some vacations, and leave a buffer for healthcare expenses. Might need to move between cities if rent gets too costly in one place. Again ACA disbanding would be the main risk.
3. FIRE - Basically the same as LeanFIRE but I can live with rooomates in a HCOL, or in nicer places in MCOL, and spend a bit more on... hm. I don't know, maybe a nicer laptop, travel, and charity.
4. CrazyFIRE - I can live almost anywhere, have a big buffer for expected short-term and old age health care expenses, and increase my travel and charity spend.
I'm doing a combination Lean/Coast FIRE, where I plan on working seasonally for causes I care about, but I don't need the money in the short-term. I'll probably get to #3, but unlikely I'll hit #4. Healthcare is the biggest unknown, and any buffer I earn will likely be saved, not spent, for that reason.