why do roads have different names or whatever they're called like road, street, avenue, boulevard etc.?

Answer 1

Traditionally, avenues run north/south, while streets run east/west. Roads are normally further out from the center of town, possibly out in what is (or used to be) a rural area. Avenues tend to be in a down town area, as well as boulevards, which are often wide with more than one lane, and landscaped in the middle. But obviously this isn't always the case. Maybe each decision is just someone's idea of what sounds good.

Answer 2

Its a way of differentiating East-West versus North-South, etc. For example, the north-south roads might be called "street", and the east-west roads might be called "avenue". Shorter roads can be called "way", etc.