Just like spoken languages, there is a wide variety of sign languages from the world over. Did you know that in Europe alone, there are 31 documented sign languages? There can be several varieties of a given sign language within a certain area or region. Some have been appropriated and adopted by another country for their own use. For example, the American Sign Language (ASL) was actually adapted from the French Sign Language (LSF), which in turn, has been adapted to several countries outside the US, such as Bolivia and the Philippines.
Excluding the International Sign, a contact variety of sign language that draws heavily on the context of the situation, two of the widely used sign languages are the American Sign Language (ASL) and the British Sign Language (BSL). ASL is used in the US and most of Canada, while BSL is almost exclusively used in the UK, with variations being used in Ireland, South Africa, Australia, and New Zealand.
One would think that as both Americans and British use English, there wouldn’t be too much of a difference between ASL and BSL. Fact is, sign languages often don’t resemble the grammar or syntax of their spoken counterparts. As such, although both have spoken English as their counterpart, users of either ASL or BSL will find them mutually unintelligible. The reason behind this is the fact that ASL and BSL share a different language family. BSL is of the BANZSL family (British, Australian, and New Zealand Sign Language), while ASL takes its roots from LSF. One would be surprised to know that as ASL shares the same family with the Japanese Sign Language (JSL). Their syntax share more similarities than ASL and BSL!
The most obvious difference between ASL and BSL would be the number of hands used in signing. ASL uses one-handed fingerspelling, while BSL makes use of both hands. Although one might assume that using only one hand will be much faster than the other, there are evidences that such fact doesn’t really matter. Proficient users of either one get through the alphabet in roughly the same amount of time.
Like the spoken language, it can thus be virtually impossible for two persons using different sign languages to understand each other without resorting to signs and gestures—much like how a Japanese speaker might talk to a French one. It’s a myth that all sign languages are universal. Each type would have its own grammar, structure, and rules; even their spoken counterpart would vary and be completely different.