In the first image, Wordsworth compares all that he observes as he looks out across the city of London with the scenery that he would observe if he were looking out on a natural area from some high observation point. In an undeveloped place, he would see "valley, rock or hill" as he looks out at the world in the early morning light. Looking out from the bridge, he sees
Ships, towers, domes, theatres, and temples lie
Open unto the fields, and to the sky,
All bright and glittering in the smokeless air.
The second image comments on the quiet and peaceful sights of the city, the same in feeling as Wordsworth experiences in nature in the early morning. He is inspired and calmed by the tranquility he sees in the city scene, just as he would be if he were viewing a wooded or rural scene with natural features instead of human works.
Earth has not anything to show more fair: Ne'er saw I, never felt a calm so deep!...The river glideth at his own sweet will...the very houses seem asleep; And all that mighty heart is lying still!