Mobile friendliness, the top priority of AEON, led to the following critical differences from Monero:
We believe ASIC resistance is ultimately futile while imposing various forms of undesirable cost. Our ASIC-friendly PoW (KangarooTwelve) allows for faster verification of the blockchain. This also helps stabilize the protocol as the need for PoW-change hard forks is eliminated.
Monero's RingCT for encrypting transaction amounts comes with a theoretical risk of catastrophic collapse of the monetary system due to hidden inflation if the discrete log of the second generator is discovered. Favoring supply soundness over privacy, we choose not to use RingCT until cryptographers invent an efficient commitment scheme with unconditional soundness. We believe practical level of privacy can still be achieved without RingCT. Not using RingCT also contributes to faster syncing.
AEON's block time is 4 minutes. This halves the number of blocks produced each day compared to Monero, further reducing the cost of running a node.
AEON's ring size is fixed to 3 which is the bare minimum needed to prevent chain reactions (link). Monero's higher ring size means more degree of obfuscation for each transaction, but it also comes at the cost of increased blockchain size and longer verification time. We choose to stick with ring size 3 until a convincing evidence against it is found.
These differences combined result in much lower cost of running a node, smaller blockchain size, and shorter sync time compared to Monero even if the difference in adoption level is factored out. While still drawing from the technical advantages of Monero and CryptoNote, AEON has distinct development goals and an independent community that enable it to thrive as its own currency.