Operate

Operate = (1) direct or control something: ‘Do you know how to operate this machinery?’ (2) perform surgery on (medicine): ‘Have you heard what happened to the last patient he operated on?’ (3) to perform a function or work: ‘ The motor operates smoothly.’ ‘The camera also operates underwater.’ (4) to be involved in military activities: ‘A militant group  is operating against the government.’

Operation = (1) the state of being in effect or being operative: ‘That law is no longer in operation.’ (2) a planned activity involving many people performing various actions: ‘They planned a rescue operation.’ (3) a medical procedure involving an incision with instruments: ‘My mother is having an operation tomorrow.’ ‘Mr. Barrett is going to have an operation on his back.’