What's the difference between a Long straddle and a Long strangle?

Both involve buying a call and a put on the same underlying and expiration, they're bets on volatility rather than direction.

• Long Straddle: call and put share the same strike price. More expensive, but the stock only needs to move a moderate amount to become profitable.
• Long Strangle: the call strike sits above the current price, the put strike below. Cheaper to open, but the stock needs a larger move to reach the same profitability.

Rule of thumb: straddles cost more and need less movement; strangles cost less and need more movement.