1. Appearance: The navel of triangle crab is triangular, while that of flying crab is round. This makes the triangle crab easy to identify in appearance.

2. Reproduction: Triangle crab is an unfertilized female crab, while flying crab has no such distinction.

3. Living habits: Flying crabs are marine and are common in shallow waters. However, the triangle crab usually lives in a mixed environment of fresh water and salt water, which means that it has more extensive requirements for the environment.

Generally speaking, there are some obvious differences between triangle crab and flying crab in appearance, reproduction and living habits.