These of course are all the same thing just different names depending on who you talk to in the industry.
So how do you go about this and start to build a website.
The domain and the name is the first thing you have to decide on.
You can be in charge of everything and hold the key to these by having the domain in your name and giving your developer access to it. Or let your developer handle it all. Which, if you can trust your developer, is a good way to do it, if you are unsure how it all works.
So, you buy the domain or get your developer to do it. Reason why you get your developer to do it is because there are a number of web developers that will call you, annoy you with emails begging you to let them build you a website.
Another reason you will get emails from other domain registers asking you to go with them it is cheaper. You even have some sending fake invoices saying your domain is due for renewal thinking you will pay it and transfer it to them.
Because all your domains are with the developer you know that if you receive any information like this it has nothing to do with you. This happened recently to a client who received an email from an American company trying to con him into paying a bill for his domain. A quick call to verify I had them, saved him some money.
Now buying your domain and choosing the name. The idea is when you set up your website you should buy both the .com and the .com.au if available. Reason behind this has always been so your opposition does not buy it and use it, also for good business it always pays to own both unless the other is being used in America being the .com.
Of course you can always look for ones your opposition have not bought, buy them and then sell them to them or use them on your website. Is this good for business. Some say it looks bad. Others say it is good business sense, I suppose it really depends which side of the fence you are on. Hence you buy both in the first place.
If you have been in a community for 15 years doing something and a person comes to town to set up something similar, you find he has not bought both domains, you buy the .com one, he insists it is bad business sense, he calls and abuses you and tells you he will make your life hell in a phone conversation. are you likely to sell it to that person. No, Of course you have every right to buy a .com domain because they are a saleable item.
Another reason you should by both.
So you choose the name you buy both domains, you have both of them directed to your website. You also might buy some that are similar or people might use to find you. That is totally left up to you.
The other thing to remember is this. When purchasing a .com.au domain if it is your name of your company and someone else has it and not using it then you have every right to demand it back, where as a .com is available for anyone and can be sold and bought many times for money by anyone. .com is an oversaw/american domain and some are worth quite a bit and will continue to be bought and sold on the market.
I know that NARRABRI.com is available for $10,000 australian dollars. A hefty price to pay to start a business. So just an example. Most are owned by companies in Singapore wanting to trade and make some money on the open market. Many have made money by owning the domain that everyone wants.
I hope this explains the domains and URL's and website names for you.