What is the difference between a hybrid and a plug-in hybrid?

A conventional hybrid carries a small battery that is charged entirely by the gasoline engine and by regenerative braking, which captures energy normally lost as heat when slowing down. You never plug it in, and it cannot travel far on electricity alone. The benefit is fuel economy in stop-and-go driving, where the electric motor handles low speeds and the engine shuts off at rest, which is why hybrids often post better city numbers than highway numbers, reversing the usual pattern. A plug-in hybrid carries a substantially larger battery you charge from an outlet or charging station, typically delivering 20 to 50 miles of pure electric range before operating like a conventional hybrid.

Which one makes sense depends almost entirely on your commute and your parking. A plug-in only earns its higher price and weight if you can reliably charge it, ideally at home, and if your daily driving fits inside the electric range, in which case you may use gasoline only on longer trips. If you cannot charge conveniently, a plug-in becomes a heavy, more expensive conventional hybrid, and research has found real-world plug-in fuel economy falling well short of ratings precisely because many owners rarely plug in. A conventional hybrid asks nothing of you and delivers its benefit automatically, which makes it the safer default for anyone without dedicated parking. Both differ from a full electric vehicle, which has no engine at all.