Stratosphere Las Vegas vs. Imperial Palace

There is no "stratosphere" on the Las Vegas Strip as a geographic layer. You're likely referring to Stratosphere Las Vegas (now rebranded as The STRAT Hotel, Casino & SkyPod), a hotel-casino located at the north end of the Strip. The former Imperial Palace (now The LINQ Hotel + Experience) is near the center of the Strip. The two properties are approximately 2.5 miles apart.