Ultra Maniac

Ultra Maniac is similar in the magical catergory in general. In CCS, it's centered on capturing the cards but it also focusses on when they're in school too. Ultra Maniac is more centered in school as well and they are both romance too. 

Because they are both a lighthearted, good-mood, episodic magical girl show. CS and UM feature a young girl with magical abilities trying to live an ordinary life, but is forced to use their powers usually due to supernatural circumstances around them. Both shows are primarily magic and school-life oriented, with a familiar balance of comedy, romance, and good wholesome fun. Some other similarities include art style, episode/plot structure, production values, adventurous nature, and more; making both shows feel very similar to one another.  

If you like ultra maniac, you will definitely like CCS. Two shows are quite similar, though CCS much much better than ultra maniac. Both are romantic in nature with both comedy and slice of life. Ultra maniac is straight story, where CCS is very deep one. Both have late confession and very sweet confession. Ultra maniac is high school show where CCS is 5th grade show. Both have character development (again CCS is way ahead in this department). And please try to watch the Japanese dub with English subbed version if possible, because English dub ruined these shows (specially CCS). 

The Ultra Maniac anime series has Nina, a witch from the Magic Kingdom who is searching for The Holy Stones, where in Sugar2 Rune the girls are taking hearts from people, both series involve witches who are sent to Earth for a purpose of collection basically, whether it is "hearts" or Holy Stones. Sugar2 Rune has a little more drama too than Ultra Maniac, and in Ultra Maniac, a "human" girl, Ayu was Nina's dear friend while in Sugar2 Rune Chocolate and Vanilla are the best friends. 

The plots are very similar as the protas go to the human world for a competition related to the magical world where they come and must hide the fact that they are a witch / magical girl. They have good teachings too. 

Its magical plot is somewhat similar since somehow the protagonists who come from a magical world to the human for a competition end up involving someone outside of it.