This type need a fibre washer, the threads start (arrowed) right from the face of the port:

This type need an O-ring, there is a recess in the face before the threads start:

Banjo and bolt with an O-ring on the pump side from Dave Dubois. Both types use a fibre washer on the bolt head side, which may have a recess as shown in this picture:

This type may need a second fibre washer (logically the recess side) to prevent the banjo bolt bottoming in the pump and failing to apply sufficient pressure to the seal, however even that was not enough when using a new recessed banjo (pre-fitted to new hose to try and minimise fuel loss during a 'hot swap' with a partial tank) so I refitted the original non-recessed which meant emptying the tank.

The banjo bolt: (Moss Europe)

The banjo has an internal channel so fuel can flow through and round the bolt to get to the exit port, the two holes do not have to be in line: (MGOC)