这就是一个there be 句型,句中有一个too...to do .结构,“太...以至于不."
其主语是:too much regional differences in vocabulary of the language
不定式to be the same everywhere 作结果状语;
too much regional differences in vocabulary of the language 是导致这个结果的原因.
句意:这门语言词汇方面的区域差别太大,以至于每个地方不尽相同.