Pre-release tags in download on 7

I noticed that the download page has “pre-release” tags on all the 7.x downloads. And “latest” on 6.3.x. Any reason? Is 7.1 considered production-grade?

I’m looking to deploy a new application. I did the dev on 6.3 but it seems that 7.1 has significant improvements. So before we start final integration testing, I’m wondering which version I should use.