I couldn't find a thread on chinos except for one from 2006 in supershoppers, so started this one.
Watched this recently.
They introduce interesting differences in chinos of the different times:
Side pocket shape
Button fly or zipper
Button material- metal or urea
Width of belt loops
Side seams double or not
Watch pocket
Fabric- Chino cloth (LHT) or weapon (West Point/RHT)
Stitching of back pockets (they call it ryotamaguchi or katatamaguchi)
Silhouette
Details start around 12:30