LogFAQs > #924608568

It's Fates that was split between three versions (Birthright/Conquest/Revelations). Aside from that they're all standalone titles.

Three Houses is being more experimental than the 3DS titles by adding Persona-esque school and calendar elements. It's also similar to Fates in that there are three stories, but unlike Fates they're all included in one package. The main character is a professor and you choose one of three houses' students to teach. This means you have unprecedented control over your units and how they grow, by deciding what classes they become, what weapons they become proficient in, etc...

Or you can just automate most/all of that process and more or less go from story battle to story battle like past games if none of that interests you.

It also appears to be much heavier on the story and world-building than the 3DS games.
---

Change is weird.