Your samples are now two flights — try Compare without flying
The training project has always let you practise every tool on real finished data. But comparing flights needs two finished projects of the same site — so the feature you were least likely to have tried was the one a single sample could never show you.
Your account now carries two samples: one site, flown eight days apart. Tick both in your Projects list and press Compare for the swipe view and the cut/fill readout, on data where nothing you do costs anything or breaks anything.
One thing you will see there, and it is deliberate: the two were built different ways — one reconstructed from raw photos, one from an already-processed export — so Compare warns you that differencing them measures the pipelines as well as the ground. Better to meet that warning here than for the first time on your own site. Read the volume in the samples as a demonstration of the workflow, not as a survey result.