Those who maintain blogs or websites, usually assign one website for each niche. But holding more than one or two websites does not mean you need to buy separate virtual real estate for each of your site. To keep things as simple and manageable as possible, it is often advised to purchase account on one web hosting site that allows you to host a number of add-on domains. In this way, you will have a single control panel through which you can administrate all the domains. You do this by either using an add-on domain or assign a parked domain name.
Add-on domain has a completely separate website that does not publicly share anything with your other websites. But on the administrative back end, it is set up in the virtual space of another main website. The add-on domain’s content is stacked in a folder named public_html. The add-on domain is registered and its name servers settings point to that of the main hosting account. To access an add-on domain (say, addondomain) you can use the following URLs: addondomain.com, maindomain.com/addondomain and addondomain.maindomain.com. Examples of add-on domains are mail.yahoo.com (where Yahoo Mail is the add-on domain of Yahoo.com). Add-on domains resemble separate websites because they have their own FTP and CGI settings, independent email accounts and web statistics. To incoming traffic, add-on domains of one hosting account look no different than websites maintained by different hosting accounts.
Parked domain names are likened with aliases because it is actually a different domain name given to a website holding a different domain name. Its main difference with add-on domain lies in the fact that parked domains do not require a website to be built, it is already there. It does not have different web stats but parked domains can have separate email addresses if the admin assigns it. Parked domains are availed frequently by business website owners who want to reserve more than one web address that promotes their products. For example, if you have a website product.com and it is popular, competitors may easily use a domain name product.net to attract more traffic. So, business website owners often reserve parked domains with .net, .com, .org and even .edu extentions.
Difference in Use
It is not fair to say whether add-on domain is better to use than parked domain name because which will work better depends on the requirements of the user. For instance, if you want to have two websites, one dealing with wedding planning and another about Android tips and tricks, it is obviously best to use add-on domains for the two. But if you have a website which targets niches coincide then use parked domain names. For example, if you have a website on Android tips and tricks and Android app reviews, then you can have a main domain, say, ‘androidworld.com’ and use the parked domain names ‘androidapps.com’ and ‘androidtips.com’ to lead to the same website.
So, in their own ways, both parked and add-on domains are both indispensable for webmasters.