This rostrum is very prominent in dolphins. Many porpoises do not live past their mid-teens. Porpoises have an intensive reproduction schedule that may play a role in their lack of longevitiy. A porpoise can become pregnant each year, give birth, and then it can become pregnant again five or six weeks later, so it can be nursing and pregnant at the same time. This can also happen in dolphins, but dolphins are larger in size and it seems their body is suited for handling such occurences, and anyhow it is less common.
Dolphins can live in an upwards of fifty years.
There are many behavior differences as well as physical differences. For the most part, porpoises are shy animals. They do not often approach people or boats. The dolphin, on the other hand, if often seen riding the bow wave of fishing boats. We rarely see porpoises at the surface unless they are coming up for a breath.