MySQL Difference between BEGIN and START TRANSACTION

I'm using RDS Aurora (MySQL 5.6) By default Auto Commit flag is enabled. I have a transaction as follows BEGIN; INSERT INTO .....;// STATEMENT 1 INSERT INTO ......;//STATEMENT 2 COMMIT; I'm expecting both the Inserts to be commited only when COMMIT is executed. But Statement 1 is Commiting as soon as it got executed. So I wanted to know What does BEGIN do here ?? I was assuming that BEGIN does the task of disabling Auto Commit , Can someone also explain the difference between BEGIN and START TRANSACTION as well.