Opensearch Upgrade and Versioning Question

Hello opensearch community, I have a question,

I noticed that there are two line of versions available for opensearch – 1.x and 2.x, both of which were updated on Dec 13, 2022. Can someone please explain the logic behind this?

I ask, because my team is currently using version 1.2.4 and we’re getting ready to upgrade it to match latest version. However, it appears that there are two choices:
Either upgrade to version 1.3.7 or upgrade to version 2.4.1 and I’m not quite following what is the right approach.

thank you for your time,
Firdaus