The difference is cadence. A session that averages below 140 steps per minute is a walk, and a session that average above 140 steps per minute is a run. Each session will be logged as either a run or walk (two different icons) in the Run Log.
In case you are interested, here are all the Pod’s built-in measure parameters…
POD START-STOP-PAUSE PARAMETERS
1) A “Session” starts when your cadence is 100 spm or more, for 6 minutes or more.
2) The Pod sees pauses and erases them. A “Pause” is a drop under 100 spm for less than 30 minutes. If a pause is longer than 30 minutes, the session will end.
3) A session is considered a “Run” when your cadence averages above 140 spm.
4) A session is considered a “Walk” is when your cadence averages above 100 spm and below 140 spm.
5) If a session is at least 60% “Running” (over 140 spm), the Pod will trim walks from the beginning and end of the session (i.e. warm-ups or cool-downs). Note: by tapping “adjust & calibrate” on the Run Detail screen, you can trim off or add back warm-up and cool-down minutes.
6) The Pod counts all walking and running within a session, as long as your cadence is above 100 spm.
7) The Pod counts every step towards the shoe life total (odometer feature) even if it’s not part of a Session.