•both have the same character art style
•both animes are of the school/comedy/parody genre
•both anime are focused on a group of students in a club
•both are a harem where the boy is situated in nonsensical moments
•both have references to many other animes that make the anime more interesting
•they are really similar in the comedic/character design way, if you enjoyed one you would enjoy the other.
Both are about an astronomy club, but while Ebiten's staff is only composed by female members, in Sora no Manimani there are also male characters.
Also, as an anime Ebiten is a little more stereotyped then Sora no Manimani.
Lots of laughs! They both contain a lot of humor based around yuri, sadomasochism, and parodies of other anime, as well as those moments when the "reality" of the show is blurred. As there are many scenes in Ebiten you are unable to differ between actual content and parody, in Maria Holic there are many times you are unable to differ between Kanako's delusions and reality.
•both have the same character design in it
•both contain a harem of school girls with 1 guy
•both contain an average plot that is okay
•both have different genres, but the comedic, school life is the same,
•if you enjoyed one you will probably enjoy the other in the comedic school life sense
Both of them are full of fan service, but when in C³ we have one mail male character, in Ebiten we have only episodical males. This shifts Ebiten in the direction of yuri. Also, when in C³ story connected with supernatural abilities, in Ebiten we have a good parody on such a genre.