Training kind is the kind of the practice you can do using Prana Breath app. It is either breathing session or meditation, and is used to highlight the main purpose of your practice.
Breathing session is the actual breathing gymnastics practice, that consists of breath cycles only, or of the combination of breath cycles and repose cycles (combining them is available for Guru version).
All 8 default training patterns are breathing sessions, as well as most of extra patterns that you can download from our wiki database.
How to choose training kind