Similarities
* Both series feature a group of underwater mermaids who transform into magical idols in order to fight against sea monsters.
* The main characters in both series are Luchia Nanami, Hanon Hosho, and Rina Toin.
* The mermaids in both series use special pearl-shaped items called "Pearls" to transform into their idol forms.
* Both series feature the villainous organization Dark Lovers, who seek to steal the Pearls and use their power for evil.
Differences
* The setting of Mermaid Melody Pichi Pichi Pitch is the human world, while the setting of Mermaid Melody Pure is the underwater world.
* In Mermaid Melody Pichi Pichi Pitch, the mermaids must collect seven Rainbow Pearls in order to save their home world, while in Mermaid Melody Pure, they must collect seven Aqua Pearls in order to defeat Dark Lovers.
* The mermaids in Mermaid Melody Pichi Pichi Pitch have the ability to transform into three different idol forms, while the mermaids in Mermaid Melody Pure have the ability to transform into four different idol forms.
* The villains in Mermaid Melody Pichi Pichi Pitch are all humans, while the villains in Mermaid Melody Pure are all sea monsters.
Overall, Mermaid Melody Pichi Pichi Pitch and Mermaid Melody Pure are two different anime series that share some similarities but also have some key differences.