The night theme is beautiful and evocative. The guitar work there is a joy to listen to. It is the stronger of the two tracks by far.
The dawn theme, I'm not feeling as much, but at the same time it does give me a sense that there's more activity going on.
For an OST, what kind of purpose it serves is very open ended because well, there've been no story details except for that one twilight photo of traffic on the submission page. If I were to consider just that photo alone, both themes do fit that setting. Just that I'm not quite sure that's your intent, because nothing else was mentioned. (Assuming that is your intention, that it's all set in the backdrop of this city picture, it works.)
All the very best in the jam!