tens of thousouds 和tens of millions都是啥意思?都是“成千上万”的意思吗,有啥区别呢?

Tens of thousands of people come to the city to attend the ten-day South by Southwest Music,Film and Interactive festivals.
tens有十的意思，Five Tens五十，Tens Years十几年来。
tens of thousands这个是成千上万，tens of millions这个是数百万

tens of millions 是什么意思? 我看了一个译文是几亿, I'm not sure, tens of millions of: 类似我们讲的“几百万”，数以千万也对。 数以

tens of thousands
成千上万；好几万
tens of millions of
数以百万