Is there any difference between Studded Leather and Breastplate if my AC is the same with both?

Playing 5e with a Rogue. To make a long story short: In my possession I have both Studded Leather armor and a Breastplate. With my 18 Dexterity, My AC with Studded Leather is 16 (12+4). But if I don the Breastplate, my AC is the same: 16 (14+2). Since neither have any disadvantage on stealth or DEX throws – what confuses me is what the difference is. My character has the money to pay for training and doesn’t need cash to the point where I need to hawk the Breastplate for coin. Nobody in the party needs it, and so the question remains:

Is there really a difference between them at this point?

Is the choice cosmetic now? Between a Rogue wearing spiked leather padding all over – or a dense plate with free-flowing arms and legs otherwise? It can’t be this simple, there has to be another angle to it that I’m unaware of. There’s no reason for a piece of medium armor and Light armor to be statistically identical.

Is one truly wiser a choice than the other? If I swap out my Studded Leather for a shiny new Breastplate, is there anything else for me to worry about other than another 7lbs on my person?

Can a breastplate be crafted with non-metal materials in Adventurers League?

According to Adventurer’s League rules, is it legal to have a nonmagical breastplate crafted for a character which is not made from metal? This breastplate should have the same characteristics as the breastplate in the PHB on page 145, but made from a non-metal substance. This is for a druid.

According to the Adventurer’s League Guide from Season 7 on page 3:

If you want your character to engage in a downtime activity, you have a number of options available to you on page 187 of the PHB.

And on page 187 of the PHB, under Crafting, it states:

You can craft nonmagical objects, including adventuring equipment and works of art….someone proficient with smith’s tools needs a forge in order to craft a sword or suit of armor.

So I take this to mean, according to RAW, that the Adventurer’s League allows the crafting of a nonmagical breastplate.

So, to reiterate my question, can this nonmagical breastplate be made from a non-metal substance?