The purpose of this research is to read the pattern of Similarities and Differences in traditional townscapes in Kyoto using Common Lisp Object System (CLOS). First we extract the distribution of signs in townscapes in terms of architectural signs, their materials and finish, from the database of townscapes, which we construct on CLOS. Then we analyze the mechanism of Similarities and Differences quantitatively by diversity index, which is used as a measure of species diversity in the field of mathematical ecology. As the result, we clarify that the patterns of Similarities and Differences are realized in multiple levels, such as distribution of signs in the whole townscape, that in each façade of a house, and distribution of façade types.