Sign Language is Not UNIVERSAL. Every country has its own sign language just like it has its own spoken / written language. Each country has its own set of vocabulary and grammar in their own Sign Language. In India, we deaf Indians use the INDIAN SIGN LANGUAGE [ ISL ] , Deaf Americans use AMERICAN SIGN LANGUAGE [ ASL], Deaf Britons use the BRITISH SIGN LANGUAGE so on and so forth.
Every country has a unique culture, style and tradition. Spoken language of every country has a blend of the culture,the style in their spoken languages and Sign language is no different. The grammatical structure of Sign Language in one entire country is usually the same. There may be a regional variation from State to State, which is very prominent in the Spoken language as well. This variation is more specific to vocabulary.