Compare overall length and individual end widths
Use the published numbers for the feature they actually measure.
Use overall length for footprint comparisons
The Silicone Studs listings identify a 12-inch and a 16-inch model. Their four-inch difference describes total length only. Look for a labeled diagram if you need to know where the extra length sits.
Check whether a width is attached to a specific end
The Blush specification for Twin Python gives a 2.25-inch width for the product. The listing does not assign a diameter to each end. Do not copy that number into a per-end comparison.
Check the exact size and SKU
Some product pages sell several sizes under one name. Match the size selector, SKU and diagram before relying on a measurement. If a width matters and it is missing, ask for the widest point of the applicable end.