1. develop into意為“發展為……”。如：

The argument developed into a bitter quarrel. 這場辯論逐漸變成了激烈的爭吵。

Their affair did not develop into a lasting relationship. 他們的曖昧交往未能發展成為持久的關系。

2. develop from意為“由……發展而成”。如：

Land animals are thought to have developed from seaanimals. 陸地動物被認為是從海洋動物進化而來的。

The place has developed from a fishing port into a thriving tourist centre. 這地方由原來的漁港發展成一個繁榮的旅游勝地。

比較：

Plants develop from seeds. 植物從種子長成。

Seeds develop into plants. 種子長成植物。