The electrolyte in lithium ion batteries is very flammable. It combusts on contact to air which is why batteries if punctured. LiFePO4 batteries don't have super flammable electrolyte; they can burn but not easily and violently.

It’s is less dangerous, because LFP has lower energy density that other lithium chemistries so which means either less energy to dissipate per kg of battery, or more surface area to dissipate the energy per joule.

Also LFPs don’t contain components with negative temperature coefficients of resistance (I.e. stuff that gets more conducive as it heats up), which reduces the risk of thermal runaway because LFPs increase their resistance as they get hot, reducing their max output power. Rather other chemistries that reduce resistance as they get hot, increasing their output power.