Well, peace and development are kind of similar. Peace stems from development. There can be no peace without development and no development without peace.
For example:
John had trust issues because of his past relationships. He met a really nice girl. His trust changed over time (development) by her kindness. John doesn't have any trust issues (peace), and he has a new girl friend :)
If John didn't meet that nice girl, he wouldn't have changed over time (wouldn't develop) and he would still have trust issues (no peace).
So If this makes more sense now, There can be no peace without development and no development without peace.
I tried to explained this as best as I could! I hope this helped! +*♡