Duplicate content is big no-no when it comes to better ranking on Google or any other search engines. It is one of many problems that many webmasters will have to face and deal with in their careers. Two of the popular ways and only ways to tell search engines that certain page is not duplicated are utilizing what are so called 301 redirect and Canonical.
What is the difference?
They might be served the purpose, that is to tell Google that we don’t have duplicated content and please don’t penalize me. However, they are used in different way under different circumstances. In a very simple term, using 301 Redirect is basically telling Google that the old page is longer exist or the url has been changed, please pass all SEO juice to the new page. On the other hand, Canonical is basically telling Google that we have multiple similar pages, please only index this page.
301 Redirect is always the preferred way when it comes to passing the existing authority to a new page or a new website. It basically states that the old page or old site is no longer exist, and we want it to be permanently redirected but we don’t have to lose all existing SEO juice on the old page or old site. In order to implement 301 redirect, often you will need to have cPanel or ftp access, and add a line of 301 http code to your .htaccess file. It can take a quite while for Google to pass all the search authority to your new page.
In short, 301 Redirect is definitely the most popular way when a page is permanently gone or removed, and it is the only way to retain the old SEO juice when your website is moved to a new domain.
Canonical is often confused with 301 redirect. However, they are quite different. You use Canonical when there are number of pages that have exact or similar content. And we all know that having duplicated content can cause big problem to your website overall ranking. Canonical is a great way to inform Google that you have similar content on the website, and ask Google only index one page.
For example, let’s say we have two pages: Page A has more detail than Page B, but most parts are simply the duplicate of Page B. If we don’t do anything about these two pages, it will become big problem to our ranking. In order to resolve this, we can use Canonical to inform Google that Page A is the preferred page that we want to be indexed.
In short, Canonical is used when you want two similar or exact pages to be available, as well as there is no way of accessing to cPanel or ftp.
So now, you have basic understanding of 301 Redirect and Canonical. Although both methods are used to avoid duplicated content and treated pretty much the same in the eyes of Google, 301 Redirect is still the preferred and most popular way when it comes to 301 redirect.