Unlike HTTP, where requests and responses are sent and returned in plain text, HTTPS uses TLS/SSL to encrypt the communication between the client and the server. This way, information and data exchange between the client and the server will have more protection against potential attacks that may intercept and alter the exchanges to their advantage.
Aside from that, here are other benefits of redirecting HTTP to https:
Traffic – all communications between clients and servers will be encrypted and secure.
SEO ranking – correct redirection types will significantly affect and improve your website’s rankings on the search engines.
Maintenance – if your site is down, you don’t have to worry about your visitors not knowing as redirecting http to https includes notifying and sending your site’s traffic to an “Under maintenance” page.