Since Bill isn't a great talker nor is he a great observer, his comments about his surroundings compared to Jake's, the narrator's, comments not only seem paltry in quantity but are paltry in content. In Chapter X of Hemingway's The Sun Also Rises, Jake waxes lyrical--within the confines of Hemingway's minimalistic style--about the beautiful surroundings:
we came out of the mountains, and there were trees along both sides of the road, and a stream and ripe fields of grain, and the road went on, very white and straight ahead, and then lifted to a little rise, and off on the left was a hill with an old castle ...
In the back seat, Cohn is asleep, thus making no comments, but Bill was awake. When Jake calls his attention to the surroundings, he looks around and responds by nodding his head. So much for deeply felt aesthetic and eloquence.
Later, in Chapter XI, Bill comments on how nice the Basque people are and then on how cold it is up where they have traveled to for fishing. He elaborates on this comment by saying:
"My God!" said Bill. "It can't be this cold to-morrow. I'm not
going to wade a stream in this weather."
He follows this up with more remarks on how cold it is and then asks for hot rum punch to warm up with because the piano playing he has commenced will not keep him warm for long. Aside from a comment on Jake's appropriation of a bottle of rum for the hot rum punch, his final comment is on how windy the surroundings are.
This comparison shows that while Jake engages with his surroundings, making observations and judgments, Bill clearly does not. He seems only to engage with his own sensory perceptions, an assessment exemplified by his exclamations over the cold, his demand for hot rum punch, and his ending comment about the blowing of the wind, which contrasts dramatically with the passive nod of his head in acknowledgment to his surroundings.