Here's why:
* Different origins: CSL developed independently from other sign languages, influenced by spoken Chinese and the culture of Chinese deaf communities. ASL, on the other hand, has roots in French Sign Language and was developed in the US.
* Different grammar and structure: Both languages have their own unique grammatical rules and sentence structures. CSL, for example, uses a "topic-comment" structure, while ASL uses a "subject-verb-object" structure.
* Different signs: While there may be some similarities in signs for basic concepts like "eat" or "drink," most signs are distinct between the two languages.
* Different regional variations: Like spoken languages, sign languages have regional variations. Within China, there are different regional dialects of CSL. Similarly, ASL has regional variations within the US.
Just like spoken languages, sign languages are distinct and have their own unique characteristics.