Both series contains realistic depiction of problems that people might face in their lives and great illustration of their mental state and changes while confronting the problems. In addition, the music and art style are excellent and very suited for these slice of life stories.
Otona Joshi is more oriented to mature audience, while 5 cm/s is perhaps more suited to younger and older alike.
Both series are stories based on actual literature. Though the audience for both are vastly different, they both take on very mature and profound themes about life. I think that anyone who appreciates the rawness of literary stories would enjoy both.
Mature, thoughtful stories about adult women living in contemporary Japan. Neither show shies away from realistic depictions of romance, sex, and failed relationships. Both have a strong sense of melancholy interspersed with levity at life's absurdities, and their protagonists make difficult and interesting decisions. Nana is long and lacks a conclusive ending; Anime Time tells four unrelated short stories. In each case it's less about the destination than the journey.
I think these animes are both intended for the same target group.
Both show different complex female/male-relationship between adults/ older adults .
Otona Joshi no Anime Time is more poetic and focuses on the women while Ristorante Paradiso shows the relationships mostly from the male perspective and has more steady art.
Both are josei/slice of life that share similar themes. Focusing on the lives of 30-something working women making their way in a modern world. The tone is different (though there is some overlapping). Otona is a somber and nostalgic character study of the four different women. Hataraki Man is more 'sex & the city', but in a good way.
Both of them are made in no-anime style. I don't mean graphic (but in Jin-Roh it's more realistic than nice). These works resemble serious movie so much like director didn't find any good actors and decided to make an anime.
Mature and realistic slice of life, female point of view.
If you enjoyed the slow pace and you are in one of those "look at yourself in the mirror" kind of moods this is exactly what you are looking for.
Slightly nostalgic, bittersweet, very enjoyable watch.
I really wish there was more like this!