None of these are dialect words. Some are neutral and some are informal. Some are used more in British English, some more in US English. Mate: This means friend or colleague, usually referring to a man. It's often used in informal contexts. It is also a very common form of address between men in the UK, used as a sign of friendliness. Friend: A neutral term. A person of either sex with whom you share non-romantic personal relationship. Pal: A slightly old-fashioned informal term meaning friend. These days it can sometimes have a slightly negative connotation ( e.g. 'That businessman doesn't pay all his taxes because he has pals in the government'). Used in both British and American English. Buddy: An informal American term meaning friend. Dude: An informal American term meaning man. Chum: Like 'pal', this is an old-fashioned informal term meaning 'friend'. It is not often used nowadays. Like 'pal', it can often be used in a negative sense to refer to other people that you think are too friendly (such as in the example of the businessman above). It is a mainly British term. Partner: This is a neutral term. In a domestic context, your partner is a husband/wife/fiance/fiancee/boyfriend/girlfriend. Your tennis partner is someone you play tennis with, your dance partner is someone you dance with, and so on. In a work context, a partner is someone with whom you are jointly responsible for a business or an aspect of your business. Colleague: A person you work with, or a person employed by the same company. A neutral term. Coworker: A neutral American term for a colleague. Rarely used in the UK. Lad: An informal word for a young man or a boy. Used mainly in the UK. In the past it was a general alternative term for 'young man', especially in the north of England and Scotland. These days it may have the connotation of an irresponsible and immature man who enjoys drinking and socialising with his 'mates'.

I will try! They are mostly words for friend and yes they are used in different countries (I am from Ireland). Colleague and coworker are just refer to people you work with. I have never used coworker - I guess it's American. Mate is generally used in Australia. Dude is definitely American and also pal I think. Chum and buddy would be more British. Partner would usually refer to your long-term girlfriend/boyfriend, but could also be used in sports terms - as in my tennis partner. Lad usually refers to a male but in Ireland we use it to refer to anyone - as in 'I'm going to the pub with the lads' - 'with my friends'