Originally Posted by Certif1ed

Deep Purple started BEFORE Led Zeppelin. While DP were touring with their Mk1 lineup, Led Zep were still either leaving the Yardbirds, in the process of forming, or supporting Frijid Pink...

As a blues rock band with organ player, they cultivated an original heavy sound that is quite dissimilar to that of Zep - the whole musical style is also worlds away. Apart from the obvious common blues rock root (Cream, and more strongly, Yardbirds and Bluesbreakers, but also many unsung Garage acts of the time), Zeppelin had a strong folk flavour on their first 4 albums, while Deep Purple went for Classical influences and hardly dipped into folk at all.