there 2 types of no hitters in MLB very few are perfect tho here's the differnce
The difference between a no-hitter and perfect game in baseball is a perfect game means 27 outs were recorded by one pitcher in succession to end a game; not a single batter reached first base safely.
A no-hitter means a game where no base hits were recorded, but at least one batter reached first base otherwise due to a fielder’s error, base on balls, or other ways.