Articulate the paragraph - Appropriate synonyms

> Though x and y were different project, but they had the same
> *interface*. That is why they *merged* together so smoothly.
>
> It proves that they had the same *aim / target*. (They were copying
> the same thing.)

How can I articulate the above two paragraphs in a better way?

It would be nice if someone can give more appropriate synonyms for the bold words.