Yes roads and streets are often used interchangeably, but it depends on the context. For example, you could say "Meet me at the end of the road/ street" and either would be correct, but if you say "Andrea is walking on the road" it suggests that he is walking specifically on the road, where the traffic would be, rather than just walking down the street/ along the pavement etc. At least, that's how it sounds to me as a native English speaker (UK). Saying that, Duolingo seems to favour American English so this often trips me up. Personally I would say "walking in/ along/ down the street" ..."walking on the street" sounds odd to me. Hey ho.