301 Redirects let you permanently forward one URL to another. One reason you may do this is if you migrate a store from one platform to another where the URL structure is different on the two platforms.
For example, let’s say you were moving from Shopify to Lemonstand.
On Shopify, your product URLs would look like this:
But on Lemonstand, maybe you set your URL structure to remove the word “products” and just put the title name after the .com:
So you would setup a 301 redirect that forwards “www.yourdomain.com/products/red-tshirt” to “www.yourdomain.com/red-tshirt” so that anyone who had the old link would reach the same product on your new site.
You can setup 301 redirects for pages, products, blog posts, categories, and tags from your old site if their URL is going to change on your new site. This prevents broken links from existing around the web (if a blogger linked to a specific product in your store for example), and it lets Google know that your URLs have changed so they can update their index of your site accordingly.
It’s a tie. Both Shopify and Lemonstand allow you to setup 301 redirects. However, read more about the importance of URL structure.