nuances - Difference between 完成させる and 完成する (transitive usage only)

Again, I am not referring to the intransitive usage of 完成する.

Examples

文を完成させなさい。
文を完成しなさい。

夢を実現させた。
夢を実現した。

From my understanding of the grammar, させる implies that you could be making other people help you along as well, but I'm not sure, it seems like in the example sentences there shouldn't be much nuance differences.