[simultsop]

Without more context can't comment on your upgrade process. But as others stated above, there's not much difference betweeb 2 and 3, except you do not get composition api on a v2 project, while you can use composables but can't go full composition api and have to stick to options api. Other than that most of v2 code would work on v3.

[SparkyMcUnicorn]

This isn't correct. I'm using the composition API on all my Vue 2 projects. It's even baked into 2.7.

https://github.com/vuejs/composition-api

[tinco]

Yeah our path to upgrade is going component by component switching them to compositional style.