The movies are very similar, Yayoi movie have more time skip, but the 2 movies have time skip about a love story, in Yayoi is more dramatic. in Hanamizuki is more normal. Very recommended the 2 movies,

I feel the movie a little bit similar, like in the end of Theathe and in the end of Parks and i had the same emotion, in Theatre is more explained there, but in Parks is more mystery about. The 2 movies are something that makes you thinka about it.

Choir group about school in the two films, which have a goal in mind. Aragaki Yui's movie is a bit more dramatic. But in both films there is a teacher involved. Cherry Blossom Memories have more romance than the other one.

Similar story about a choir group. And have a love story like the drama series.
Recommended if you like something related to music

Quite similar. The two have their points of toxic relationships.
Although in "Love at least" toxicity is taken to another level.

Mimi-sensei and Yaeko-san have some resemblance. They also do very similar internal monologues. And their personality is a bit similar although Mimi-sensei is more serious.
But yes, Haru-san always is given this kind of characters in the last time. It suits her very well.

People separated for a certain time.
Without giving spoilers I see them quite similar. Although the movie "Ito" the gap is longer than in "Soshite, Ikiru".