What are the practical differences between these web3.py methods for sending a transaction? w3.eth.sendTransaction({}) w3.eth.sendRawTransaction(signed_txn.rawTransaction)

I am trying to send ERC20 tokens in python with web3.py using a local private key. With this code I can send ether: w3 = Web3(HTTPProvider('https://api.myetherapi.com/eth')) signed_txn = w3.eth.acc...