Semi-registered mail (준등기)
"semi-registered mail" is one of the postal services provided by post offices in Korea. The postal service is similar to registration, but it is offered at a lower price than regular registration, and it is possible to track the delivery of mail and verify the identity of the recipient. However, there is a risk of loss because it is not a direct delivery method but is put in the mailbox without any text or notice.
Half-price Courier (반값택배)
"Half-price Courier" is one of the delivery services offered in Korea. It is offered at a lower price than an ordinary courier service, which in most cases takes four to five days more than an ordinary courier service and requires a direct pick-up at a convenience store, so it is not recommended if you are using a Korean Address or Bunjang proxy.
Therefore, "semi-registered mail" means relatively cheap among Korea Post services, and "half-price courier" means courier services that are offered at a lower price than regular courier services.