There are two types of ramen soups in Japan. They are called "Kotteri" and "Assari". "Kotteri" and "Assari" are adjectives in Japanese. The soup of "Kotteri Ramen" is thick, rich and oily. The soup of "Assari Ramen" is the opposite to the kotteri. Below are the pictures of the two types of soups.
You can find the difference in the transparency of both soups. When I was young, I really liked "Kotteri Ramen" but my preference changed when I turned 40 years old, I now like "Assari Ramen". "Kotteri Ramen" and "Assari Ramen" are not commercial names. Each ramen restaurant has their own commercial names.