The difference becomes apparent when you connect or combine organizations using the same private range. It's a lot simpler to route networks (not globally, privately) when the ranges are unique. There's no NATs, double NATs, and other nonsense to deal with.
Even without this, it's a lot simpler administratively. I have about 20 AWS accounts, all with their own VPCs, all using the same 10.0.0.0 block because... well.. nobody thought about this. What do I do if they need to communicate? (They probably won't, but...)
Even without this, it's a lot simpler administratively. I have about 20 AWS accounts, all with their own VPCs, all using the same 10.0.0.0 block because... well.. nobody thought about this. What do I do if they need to communicate? (They probably won't, but...)