Apartment and Walk-up apartment

Apartment noun - A room or set of rooms in a private house or a block used as a separate dwelling place.

Walk-up apartment and apartment are semantically related. In some cases you can replace phrase "Walk-up apartment" with "Apartment", this terms are similar.

Walk-up apartment noun - An apartment in a building without an elevator.

Apartment and walk-up apartment are semantically related. You can use "Apartment" instead a noun phrase "Walk-up apartment".