Isn't there a big difference between "designed" and "developed"? For instance the whole testing phase? Which doesn't mean it is not impressively fast, but stil

Isn't there a big difference between "designed" and "developed"? For instance the whole testing phase? Which doesn't mean it is not impressively fast, but still it's not done in a week. Plus testing the covid vaccines was quick because there were many many people to participate in the tests.