There is no significant difference between somebody and someone or anybody and anyone. The forms with –body are very informal.
The difference between somebody and anybody or something and anything are the same as the difference between some and any. Somebody, someone, something, somewhere etc., are used in affirmative sentences. Anybody, anyone, anything, anywhere etc., are used in questions and negatives.
- There is someone on the phone.
- Did anybody phone?
- I didn’t find anyone there.
- Let’s go somewhere nice for Christmas.
- I don’t want to go anywhere.
- I’m starving. Give me something to eat.
- We haven’t got anything to eat.
Note that the expressions everybody, everyone, anybody, anyone, nobody and no one are singular.
- Everybody has come. (NOT Everybody have come.)
- No one understands me. (NOT No one understand me.)
The word somebody normally refers to one person.
- Somebody wants to talk to you.
The plural pronouns they, them and their are often used to refer back to somebody and anybody.
- If anybody wants to join the club, they should contact the manager.
- Somebody has left their bag on the bus.
In a more formal style, we can use ‘he or she’ instead of they.
- If anyone calls tell him or her that I am away. (More formal)
- If anybody calls tell them that I am away. (Informal)