To answer this question, we must first know the general height of street lamps. Generally speaking, the height of street lamps is between 3 and 6 meters, and the specific height will vary according to different roads and environments. Therefore, we can assume that the average height of street lamps is 4.5 meters.

Then, the height of Xiaoming is 1.7m, and the height of the street lamp is 4.5m We can calculate the height difference between Xiaoming and the street lamp.

The height of street lamp minus Xiaoming's height is 4.5m minus1.7m, which is equal to 2.8m.. So the height difference between Xiaoming and the street lamp is 2.8 meters.

This height difference can make us better understand the height relationship between Xiaoming and street lamps. Xiaoming stands under the street lamp, which is high above, giving people a solemn and safe feeling.

Besides the height difference, we can also think about the relationship between Xiaoming and street lamps from other angles. For example, Xiao Ming stood under a street lamp, and the light of the street lamp lit up his surroundings, bringing him light and warmth. Street lamps exist not only for lighting, but also to symbolize hope and guidance.

In a word, Xiaoming is 1.7 meters tall and the street lamp is 4.5 meters high. The height difference between them is 2.8 meters. This height difference is not only a number, but also has a deep meaning. It makes us think about the relationship between people and the environment and the pursuit of light and hope.