A controversial subject that creates a lot of confusion and debate, understanding a bit how the two work:
Redirect 301
Tells search engines that the page is no longer at that address and has moved permanently to a new page. It informs the engines to remove that page from its index and index the new page. This has always been the default for permanent page redirection, it tells users that the original page is no longer relevant and that the content is on the new page.
Common Problems: If you do not have access to the server side it is not an option. Another disadvantage is that search engines can take a little longer to reach the new page. Incorrect use can also cause problems, for example by redirecting all pages from an old site to the main page of a new site, this undermines the relevance of all search traffic and can result in a high bounce rate. p>
When using 301
- By default - this is the preferred redirection method
- Pages that are being permanently moved or replaced
- Domains that are permanently moved
- 404 pages and expired content (assuming the relevant content or
a page exists)
Canonical
Informs search engines that there are page versions, plus to keep indexing only the favorite version. Tells that other versions will be available for people to visit, but only keep the index of the page preferred. Although incorrectly used as an alternative to 301 is a completely different approach. Unlike the 301 that physically sends the user to the new page, the canonical serves only to inform the search engines. When you have pages with similar or very similar contents is when you should use canonical, example:
You have two pages to list products in your store, one list of products alphabetically and the other by price, and both have different URLs. If so, search engines can index both. If your favorite page is the one that orders by price, you place the canonical in the alphabetical page and informs that the price is the most important.
Common Problems: It's just a suggestion, although engines take into consideration, they are not required to follow. The most common misuse of the tag is when it is implemented on pages that do not include a large percentage of the same content as the canonical page. Unless they contain considerable piece of duplicate content, it probably should not be used. Another common misuse occurs with multiple related pages. For example, you have written a blog post that has been split into several pages with your own URLs, reporting only the first page of the post even though the others contain relevant content, will make search engines never ever index the rest.
When to use Canonical
- When 301 can not be deployed, or takes a long time
- Duplicate content, but keep all active pages
- Dynamic pages with multiple URLs on a single page
- Cross-domain considerations where both sites are similar, but
needs to stay active
SOURCE in English
