Kuttsukiboshi

Both are centered around the relationship between two girls 

Both series are shoujo-ai and very beautifully animated.  

Both are Shoujo Ai Both have an element of sci-fi / supernatural Fragtime is tamer than Kuttsukiboshi, but the latter isn't hentai. If you like short OVA / films with yuri and super powers (for lack of a better term) I would recommend either of them.  

Yuri genre. Pretty much the only difference is that Kuttsukiboshi is shorter and Sakura Trick has more comedy in it. 

One is slow and steady, the other is intense feelings. Though, despite this, both yuri series are able to be good at providing some kind of sentient stories in a short timespan. More true for Candy Boy but Kuttsukiboshi had its own ideas and such. 

Passionate (kisses). Kuttsukiboshi and Citrus know how to deliver some intense passionate relationships between two lovers. Although Kuttsukiboshi is a short OVA compared to the fully developed story that is Citrus, I'd say both are similar stories from what I remember, in two lovers coming to understand, especially with the varied lifestyles of the more troubled protagonist to their respective peer.  

Here be the love two females give to each other love. However, AdaShima is more wholesome and innocent than the deeply intimate Kuttsukiboshi's love. 

Both are shows about a Yuri relationship (mild in Madoka but borderline-hentai in Kuttsukiboshi) that share an almost identical ending. 

Not has an extensive argument as Strawberry Panic!, but has great yuri scenes like this series (and more fanservice) 

It is romantic yuri , but have adult scenes too ^^ 

Yuri shows that included supernatural elements for no good reason. Telekinesis and alien fail to contributes anything to romantic part of the show. 

Both are very sweet and sometimes sad animes that revolve around a yuri relationship, there are also supernatural elements in both although there is far more in Yami to Boushi.  

They all show school life with yuri genre. Inugami-san to Nekoyama-san is light-hearted and fun without adult scenes.