No problem identifying these pins! Got the years of service right on there. What variation there is involves the presence or lack of stones on the 5 and 10 year pins, and blue or green enamel on the 10 year pin.

Five year pin. Older style with single diamond.
Five year pin. Without diamond.
Ten year pin. Older style with two diamonds, green enamel. I've been told (by someone who knows about this stuff) that when Douglas stopped putting stones in the 5 and 10 year pins, they started using green enamel rather than blue on the 10 year to distinguish it from the 5 year. This pin seems to contradict that, but I suspect that the stones were awarded after the fact.
Ten year pin. Older style with two diamonds, blue enamel. Only one of these I've ever seen. It was awarded to an employee of the DAC Santa Monica plant.
Ten year pin. Newer style without diamonds.
Fifteen year pin. Three diamonds.
Twenty year pin. Four diamonds.
Twenty Five year pin. Five diamonds.

Interestingly, the style changed radically at this point.

Thirty year pin.
Thirty Five year pin.

Wings promo pin. Very small.
Son in Service WWII pin.

Believe it or don't, but a 3 year DAC service pin was made. I'm told this was given to Rosie the Riveters at the end of WWII.