1. develop into意为“发展为……”。如：

The argument developed into a bitter quarrel. 这场辩论逐渐变成了激烈的争吵。

Their affair did not develop into a lasting relationship. 他们的暧昧交往未能发展成为持久的关系。

2. develop from意为“由……发展而成”。如：

Land animals are thought to have developed from seaanimals. 陆地动物被认为是从海洋动物进化而来的。

The place has developed from a fishing port into a thriving tourist centre. 这地方由原来的渔港发展成一个繁荣的旅游胜地。

比较：

Plants develop from seeds. 植物从种子长成。

Seeds develop into plants. 种子长成植物。