Both anime are second seasons.
Both are popular moe anime.
Both are about cute girls doing cute things.
Both have very memorable and very funny scenes.
Both are an improvement from the first season in my opinion.
Yuru Yuri is focused more on humor, while GochiUsa is more focused on moe.
Second seasons of popular "cute girls doing cute things" slice of life anime that are very lighthearted and funny, not to mention the moe atmosphere.
Both are based on Manga Time Kirara manga
Both Ayaya and Rize share the same seiyuu, and so does Karasuma-sensei and Chiya.