"As per" is legal jargon used mostly by judges, lawyers, contract writers, and policy makers. Lawyers use these phrases out of habit or perhaps tradition as all legislature goes back to Roman times when everyone spoke Latin ("as per" most likely comes from words in Latin.) You can expect the words "as per" to pop up in any kind of contract, rental agreement, insurance policy, etcetera. Example: "As per the rental agreement, the car will be returned with a full tank of gas otherwise the client will be billed for any missing gas." "According to" is a much more everyday phrase, and is used widely by intellectuals who discuss the analytical works of others: for example, "According to Nietzche, what doesn't kill you makes you stronger." Also, things can go "according to plan" which means that they result as expected. Also, in conversation we say "according to Raymond, she is very smart and well qualified to be a teacher." I hope this helps you understand the difference in usage and meaning.