"HEV" means Hybrid Electric Vehicle, and "PHEV" means Plug-in Hybrid Electric Vehicle. Both an HEV and a PHEV use a gas engine and an electric motor/battery system in tandem. An HEV typically only uses onboard systems like regenerative braking to recharge the electric motor's battery. Meanwhile, you can plug a PHEV into a power source to directly recharge the battery. PHEV models will typically offer all-electric driving capabilities, while HEV models are typically limited to the combined power output.