一、意思不同

1、on business：on business的意思为为了公事，出差。

2、in business：in business的意思为经商；在经营；在商界。

二、侧重不同

1、on business：on business侧重于行为。

2、in business：in business侧重于立场。

三、用法不同

1、on business：I presume you're here on business. 我想你是来这儿出差的吧。

2、in business：In business, it's every man for himself. 生意场上都是人各为己。