An isthmus is a narrow strip of land that connects two larger landmasses, while a strait is a narrow body of water that connects two larger bodies of water. In other words, an isthmus is a land feature, while a strait is a water feature. Examples of isthmuses include the Isthmus of Panama and the Isthmus of Corinth, while examples of straits include the Strait of Gibraltar and the Bering Strait.