Usually a new term emerges and it becomes necessary to add a qualification to an old word for disambiguation.
examples:
- "mono sound" versus "stereo sound"
- "analog watch" versus "digital watch"
- "acoustic guitar" versus "electric guitar"
- "slow food" versus "fast food"
Best Answer
You have named textbook cases of the retronym, which AHD defines as
Language Log and others ascribe the term ca. 1980 to Frank Mankiewicz, a writer and Democratic political strategist who was later head of National Public Radio. You can find a large collection of them at Retronyms.org.
For a related phenomenon, see Word that means “outdated name”.