The opposite of public is private and private can also mean personal. The word personal is an adjective; it means something affecting a particular person, or relating to an individual’s private feelings and emotions, or belonging exclusively to a single person. Examples given below will illustrate how “personal” can be used.

• When disembarking from the plane, please take all your personal belongings with you. (When getting off the plane, make sure you take your spectacles, overnight bag, books, passport, tickets etc. all items which belong to you.)
• I do not wish to discuss this matter with you. It is a personal matter between my wife and me. (It is a private matter shared only between my wife and me.)
• My personal opinion is that Linda and John are not suited to each other. (My private opinion which is perhaps not the public opinion is that Linda and John are not suited to each other.)
• My personal experience of the in-flight service was not very nice, but others seemed happy and satisfied. (My own experience but not necessarily that of others, was not very nice.)
• John wanted to buy a car but the dealer would not accept his personal cheque. (The dealer accepted only company cheques not those in the name of a private individual.)
• Martha is a superb cook. She adds her own personal touches to the recipe that makes her food outstanding. (Martha adds her own ingredients which are not part of the recipe, that make her food outstanding.)
• This is a public debate. Please do not make personal verbal attacks on the participants. (Please do not criticise the character, appearance or any peculiar mannerism of the participants.)
• Please do not ask me any personal questions. My life is very private. (Please do not try to probe into my private life.)
• At the interview, Jane was more concerned about her personal appearance than how she could answer tricky questions. (At the interview, Jane was more concerned about how she looked rather than how she could answer a tricky question.)
• My personal feelings are that I made a wrong choice in careers, but I would never tell anyone that. (My private feelings are that I made a wrong choice in careers, but I would never tell anyone that.)

Personnel sounds very much like personal but it has a completely different meaning. Personnel is a collective or plural noun. It means the people who work for, or the staff of, a particular company or organisation.

For example:-

• ABC engineering has 5000 personnel. (ABC engineering has 5000 people working for them.)
• 50,000 military personnel were stationed in the area. (50,000 employees of the military were stationed in the area.)
• The personnel manager of Microsoft, London, informed me that I had got the job. (The person who looks after hiring and welfare of all the employees at Microsoft, London, informed me that I had got the job.)
• Women personnel in the police force are less than 50 percent. (Women constitute less than 50 percent of the police force.)
• The project to build a dam was delayed because the personnel working on the details were reduced to less than half. (The project to build a dam was delayed because the number of people working on the details was reduced to less than half.)
• The flying personnel of an airline are paid much more than the ground staff. (The people who take part in flying an aircraft, such as the hostesses, pursers and pilots, are paid much more than those work on the ground.)
• Personnel of the United Nations aid agency distributed food to the refugees. (People who work for the United Nations aid agency distributed food to the refugees.)
• It serves no purpose to get personal with police personnel! (It serves no purpose to make comments on the behaviour, appearance, or speech of persons working in the police force.)
• The personnel of IBM attended a convention in Singapore. (The people working for IBM attended a convention in Singapore.)
• Raises in salary are decided by the personnel manager of the company. (Raises in salary are decided by the manager who takes care of welfare and hiring of staff.)

To sum up, “personnel” are people but “personal” describes something that belongs to one particular individual and no one else.