Difference between armament racks, pods, ejectors?

[rwbishUP]

Could someone who is savvy in mil aviation and armament, tell me the significance in using different types of weapon racks, pods and ejectors? That carry the same type and amount of armament? 

I've tried searching for what the purpose is, but can't find anything with a good explanation. i.e. The, LAU-68 & LAU-131 rocket pods. I went to Arnold Defense products page and looked at data sheets. And, I can't find a difference between the models.  

[Dragon1-1]

In that particular case, it's fire protection. LAU-68 is used by the USN, while the LAU-131 is used by other services. The latter also has connectors both at the front and rear, which is useful on some airframes, but not on ones that USN uses. The big difference, though, is the insulation that LAU-68 has. This greatly increases the time it'd take for the rockets inside to cook off if they ended up in a fire. On a crowded aircraft carrier, this can mean the difference between an extinguished fire and a massive explosion, since on a carrier there's a lot of ammo in close proximity, surrounded by thin metal walls, and nowhere to run. USAF ordies have the luxury of being able to hop into a hummer and floor it until they're on the other side of the airfield if the ammo dump starts smoking. USN doesn't, so they put more emphasis (and money) on making sure their ordnance takes a good while to blow up from heat, giving them a fair chance of putting it out.

In general, the reason can usually be found in seemingly minor differences between the launchers. There's usually something that might seem inconsequential, but is actually an important factor for a given service to choose one over the other. It's not only capacity, but data connections (the reason why you don't see JDAMs on TERs very often, they need a dual "smart rack"), fire protection, location of connectors, stuff like that.

[rwbishUP]

Thank you @Dragon1-1. I've wondered that since I started playing, DCS. Makes perfect sense.