Written English is about the same in both the UK and the US.这里为什么要用written?

Written English is about the same in both the UK and the US.这里为什么要用written?

written：书面的,成文的
Written English：书面英语,英语书面语

written English 表示“书面英语”
句子意思：
英语书面语在英国和美国基本上都一样。

这里是强调书面英语,
因为英式英语和美式英语的不同主要是发音不同,所以这里用written做定语强调是书面英语.