OK, from someone who had boots on the ground, the airplane deck and ship's desk.
MOS 0451 is Air Delivery. (a lot of parachute packing there
MOS 0441is Logistics (read "general" unit logistics)
MOS 0431 is Embarkation. Lower ranks this is ship loading and full accountability of all unit inventory.
At E-7 (Gunnery Sergeant) the o431 and 0441s merge into one MOS 0491.
Caution: I was USNR and was working to become a draftsman but settled on being a Radar Operator to get some traction (rank). For ease of training I changed to ET (Electronics Technician) only to sideline myself back to drafting. I also had studied the USN extensively.
After joining the Marines (reserves can make the switch). as a Squadron 0431, I did ALL the logistics functions of the unit from ordering operation and maintenance supplies to accounting for everything the squadron after serving for about 2 years as an Aviation Electrician.
An 0431 does not have a minute to themselves - if they do, they are not doing their job. Training is weak at best and hard. A loggy or embarker can not rest on their laurels.
Just prior to my end of my contract, I went looking for a job to make the exit. One company did not need electricians but the supply type experience they needed yesterday.
Log jobs are out there now, but everyone thinks you are about the High School drop-out class and the jobs suck as does the pay. That aside, I used to scare the heck out of my supervisors with what I could do. Every experience I had had served me well later on. I was able to identify parts that others could only guess at. In one case, I had a supervisor ask if I had ordered a specific item. I told him that did not seem to be a priority with the requesting site - so no I had not ordered it. He was UPSET! After lunch I was back in his office to have my tail-feathers trimmed. He asked again if I had "failed" to get that part. I said "No!" He said, well this morning that is not what you told me. I stated again that it had not been a priority and that at that point I had not gotten it. He asked what had changed. I stated he appeared to have made it a priority. For that reason, I had gotten it and it was shipped and would arrive in 3 working days to the site. He was floored. Didn't know if he should continue with and chewing me out or compliment me for such fast action. I gave him a copy of the shipping documents. Again, he was floored!
So, yes, the Marine 0431 or 0441 teaches a lot. However, to be better than one's peers, everything one runs across, pay attention, learn and at least mentally file it away. One needs an analytical and a creative mind
When things go wrong, everyone wants to blame the loggy. For what they paid, I was canned because I did not put up with management's stupidity. Company Policy and Procedures stated that a Buyer (I wasn't a buyer) had 30 days to procure an item. It took me on average about 5 days from receipt of request to getting it to the buyer - and I was too slow. I showed them the Company P&P which showed the Buyer had 30 days to act. I then showed them my interaction with the buyers, who, using my research, got the item on order within 3 to 4 days. I even got the required 7 signatures to move the request from my desk to the buyer's desk in that average of 5 days (longest was 7 days). My experience as a (Military) U.S. Customs Agent also helped after my days in uniform. I was in England, procured an item for a u.S. Government contract in Maryland, USA. That site manager was stunned when he got that item within 72 hours of his request! Item was in the mail less than 24 hours and went through British and U.S. Customs to boot.
Sorry, I did not mean for this to be an extensive rant.