A 301 redirect is a permanent redirect process from one site to another or one page to another page. This is an implementation of code to send your users from one URL to another automatically. Actually, the redirect practice is an effective way to send the messages to both your readers and the search engines system about the fact that the page they are looking to visit or index has already been removed. In this case, they can be pointed to the new page automatically without the possibility of meeting the 404 error.
With 301 redirect procedure, you have chance to change you URLs to another, which may be friendlier or displayed in the string as you want (with third party adjusting it) while old entity’s addresses still work normally. If you use 301 redirect, your customers can find your website by both old and new URL. Simply, you can understand that when someone clicks to your store’s old address (or any product URL) or type it on google search bar, they will be automatically led to another page which is active with what they are looking for and represented by new URL. 301 redirects can help your site to increase reference URL to your page. The practice eliminates the case of meeting 404 page not found error. This thing also works even you remove your old site permanently. In addition, corresponding links generated by new site will be given equivalent PageRank as the old ones. Old URLs will be moved and saved in target site with respective new URLs. And the most important thing is that old and new URL have the same domain.
The significant difference between Migrate SEO and 301 redirect is that with SEO, your products will be displayed under 2 different addresses, but just only one in 301 redirect.
301 redirect is often used for hosted target carts such as Shopify, Bigcommerce, Weebly, Squarespace, etc.