The more I read about POA, the less impressed I get.
POA is simply an Ethereum side chain that uses Proof of Authority consensus. Aion features a number of advancements from Ethereum, particularly the FastVM/AVM, spoke chain creation, custom scripting language, hybrid DPoS/PoI consensus model, and of course bridging between disparate blockchains that allows transfer of value AND logic.
POA uses 12 validators (
https://github.com/poanetwork/wiki/wiki/What-is-POA) (17 registered (
https://validators.poa.network)) which are all public notaries, so consensus is centralized and vulnerable to a number of exploits and attacks. POA's token bridge only uses 3 validators, and is subject to daily use limits due to attack vulnerabilities.
POA's token is an ERC677 (
http://blockchainers.org/index.php/tag/erc-677), which is basically an ERC20 with a transferAndCall function added. This token standard was built specifically with backwards compatibility in mind (i.e. to be converted back into ERC20). POA's "token bridge" just converts from a barely-more-advanced version of an ERC20 back to an ERC20. The ERC677 and ERC20 tokens are so similar, they can be stored in the same wallet address.
Aion's coins feature an upgraded address system (
https://blog.aion.network/aionaddresssecurity-ff4362196b24) for additional security. Moving between Aion's unique address convention to ERC20 and back presents a more complex challenge.
Importantly, as far as I can tell POA has no other interoperability functionality in development or even planned.
