With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: Since 1969, Jersey and Guernsey have operated postal administrations independently of the UK's Royal Mail, with their own postage stamps, which can be used for postage only in their respective Bailiwicks. Despite this, UK stamps are also valid, but mail to the islands, and to the Isle of Man, is no longer charged at UK inland rates. It was not until the early 1990s that the islands officially joined the UK's postcode system, Jersey postcodes using the initials JE and Guernsey GY.
text_B: Would mailing a package to Guernsey cost the same as mailing it to somewhere in inland UK?
NO.