Backup snapshots are a great implementation but for me, the only way of recognising one is by the time of last modification respect the other backups. Maybe adding "(snapshot)" at the end of the name would be a great addition to snapshots.

There is a flag in the metadata, I'd recommend using an application that helps you manage these, future versions are likely to get more complicated with even more metadata.

We will likely release a companion mod for a GUI eventually, but right now CreeperPanel and FTBApp provide GUI's for managing the backups.