What is one way that the author makes a distinction between the first transcontinental railroad and the first transcontinental passenger flights in 1936

by explaining how much faster the first transcontinental passenger flights were

The correct answer to this open question is the following.

One way that the author makes a distinction between the First Transcontinental Railroad and the first transcontinental passenger flight in 1936​ was by explaining how much faster the first transcontinental passenger flights were.

The author says that the first transcontinental passenger flights were more expensive than traveling by the transcontinental train. Not all kinds of people could travel by air. So that is why cars became popular years later. Traveling by road was something that Americans liked to do, and the author set the example of traveling Route 66.