The large arrow on the left points to a good example of peribronchial cuffing. Peribronchial cuffing simply means that some edema fluid has extravasated from the vessels around the bronchi and outlined them more clearly. The film on the right was taken after treatment and shows marked reduction in peribronchial cuffing.

Look at the apex on the left. Both sets of arrowheads point to Kerley A lines. Note the enlarged indistinct hila and the increased flow to the upper lobes ("cephalization of flow").