In the poems 'Echoing Green' and 'London' by William Blake, the poet sets out landscapes and scenes in order to get his readers thinking about the circumstances. Each environment is different and so Blake uses thought-provoking images to get readers to think about the issues. for example, in 'Echoing Green' one of the things a reader may be prompted to think about is the changing face of the English pastoral countryside and way of life due to increasing mechanisation and the gradual population drift to the towns. in 'London' the reader may be prompted to think about the role of the establishment in the care of the poor and the weak who have migrated to those very towns and found not work and progress but poverty, vice and destitution.
In my opinion, Blake is trying, through these two poems, to get readers to see the contrast between rural life and life in the city.
If you look at "Echoing Green," it shows very pleasant scenes. It has kids playing and old people watching them. The old people are thinking happily back to their own youths. All of this is happening in a village with birds and trees.
By contrast, there is nothing happy in "London." Everything about that poem shows people hating life.
So I believe that the two poems are meant to show that country life was better and happier than city life.