Xert Mobile (XM) is the original Android app from some years back.
Xert EBC is the new version which has most of the features of old app plus some new ones such as Sessions support.
You should not need to calibrate your power meter as powermatch is automatic with EBC.
EBC will eventually replace XM once all the core features of XM have been added.
Quick Start Guide: EBC – Xert (baronbiosys.com)
Episode 23 - What is this Xert EBC thing? by Xert Breakthrough Lab (soundcloud.com)