What is the difference between a Concept and an Upgraded/CCU'd ship, and how does it affect the melt value?

There isn’t a difference in the game. For example a Concept Sabre and a ccu’d Sabre are the same in the universe. The difference comes in cosmetics. Concept ships are rarer as they only are sold once and they usually come with a few extra hangar flairs. Additionally if you want to “melt” a concept ship, you can buy it back from your buyback list at any time. This is not possible with an “upgraded” ship as you will only be able to buy back the base ship that was upgraded.

When you see ships and vehicles tagged as 'CCU'ed,' this means they're built using warbond upgrades which were purchased at a discount. This results in a lower 'melt' value (the amount of RSI credits you'd get if you exchanged the item) compared to the current retail price.

However, don't worry, this doesn't affect the item's upgrade value at all. The upgrade value remains equal to the item's full retail price on the RSI store. This means you can go ahead and upgrade as if it were at full retail value.

But, be aware, if you decide to swap the item for RSI credits, you'll get back less than the retail value due to the lower melt value. We should note that we can't approve refunds based on the melt value of CCU'ed items being less than the retail price. Essentially, the CCU'ed ships and vehicles we sell are intended to be kept or upgraded, not traded in for RSI credits. If you choose to do so, that's at your own risk."