The difference between ERC20 and ERC23. ERC20 is already existing token standard used by ethereum tokens. ERC23 is a new version of token standard.
1.Eliminates the problem of lost tokens which happens during the transfer of ERC20 tokens to a contract (when people mistakenly use the instructions for sending tokens to a wallet). ERC223 allows users to send their tokens to either wallet or contract with the same function transfer, thereby eliminating the potential for confusion and lost tokens.
2. Allows developers to handle incoming token transactions, and reject non-supported tokens (not possible with ERC20)
3. Energy savings. The transfer of ERC223 tokens to a contract is a one step process rather than 2 step process (for ERC20), and this means 2 times less gas and no extra blockchain bloating.