only to引导的结果状语从句和现在分词引导的结果状语从句有什么区别?

only to引导的结果状语表示是意料之外的结果.比如说什么They arrived at airport,only to find the plane had taken off.他们赶到机场后发现飞机都已经起飞了 说明是没有想到的结果那 just to 和 only to 有什么区别？just to 是正要做比如we are just about to talk with him