This was my thought. They were 3 different bands across 4 line ups.

In Jr. High and high school I would hear Machine Head and other hits from the Gillan era. I'd hear Hush and Kentucky Woman but somehow never heard it was the same band that did Smoke On The Water.

They reunited when I was a senior and that's when I found out about the other line ups. I liked the other line ups, but never listened to them as much as the Mark II line up. Building a legacy with line up changes can be tough enough, but building it with conflicting sounds is even harder.