SAE J514 was originally named JIC 37° Flare. JIC stands for Joint Industrial Commission, which is now defunct, and the seat of the connection is 37°. This connection is especially common in fluid power systems. Since both the male and female halves have a 37° seat, the connection takes place in the contact between the male flare and the female cone seat. The threads hold the connection together mechanically, and this connection can be used with flared tubing.
The SAE J512 is also called SAE 45° Flare, as both the male and female portions have a 45° seat. Most often this connection is made of brass, and is very common in refrigeration, automotive, and truck piping. When screwed together, the seal takes place between the male flare and female cone seat, and this connection is held mechanically by the threads. This connection can also be used with flared tubing, just like the SAE J514.