Look at the details
Scale is a useful starting point when comparing figures. Check the stated dimensions rather than relying on a photograph without context. Graphic treatments, packaging and condition can distinguish editions; record the identifying information if you keep a collection catalogue.
Keep a useful record
For a collection, save the exact item name, identifying details and condition notes alongside your own photographs. For daily use, keep the care or setup instructions somewhere easy to find. A clear description is more useful than a broad category name when you return to a piece later.