I agree with the other commentator that this is a method of transferring 100% of your traffic to another version of your app.

Whereas a blue-green has a controlled and/or proportionate transfer process. For example, getting 25% of your traffic to use the new version - monitor it for a while to check stability etc and then slowly migrate the rest.

I appreciate using DNS could reduce the transfer time as it's less than an in-line upgrade depending on use case.