这两句话没有区别。

在表示“比......多[大]一倍；是......两倍”时，double和twice的意义是一样的。如：

He earns double my salary. 他赚的薪水是我的两倍。（《21世纪英汉汉英双向词典》）

This is double as much as that. 这个是那个的两倍。（《21世纪英汉汉英双向词典》）

I have ordered double the amount of coal that we ordered last month. 我已经订购了我们上个月订购的煤炭量的两倍。（张道真《现代英语用法词典》）

I'm twice your age. = I'm twice as old as you are. 我的年龄比你大一倍。（《21世纪英汉汉英双向词典》）

She did twice as much work as her brother. 她干的工作比她弟弟干的多一倍。（《牛津高阶英汉双解词典》）

This room is twice the size of that one. 这间屋子有那间两个大。（《现代汉英综合大词典》）