What is the difference between a straddle and a strangle?

A straddle buys a call AND a put at the same strike price and expiration — it profits from large moves in either direction. A strangle buys a call and a put at different strike prices (out-of-the-money), making it cheaper but requiring an even bigger move to profit. Both are long-volatility strategies used when you expect a large price swing but are unsure of the direction.