A comparison table can look precise while comparing incompatible numbers. One column lists battery capacity, another lists hours of use; one package size is measured before dilution, another after preparation. The tidy grid does not make those figures equivalent.
Before writing the table, decide which customer question each row answers. “How much does it hold?” is different from “How much space does it occupy?” Give each a separate label and a consistent unit. If a specification is missing, mark it as unavailable rather than filling the space with a flattering adjective.
Build one row that passes a fairness check
For an invented storage-box comparison, all external dimensions might use centimetres in the same order: width, depth and height. Capacity can occupy another row in litres. Do not place the lid-on height for one box beside the body-only height of another without explaining the difference.
Likewise, compare prices for a clearly identified quantity and variant. A pack of two is not directly comparable with a single item unless the row says so. A calculated unit price can help, but retain the pack price because that is what the customer may actually have to pay.
Keep a source record for every factual entry: the product page or supplier document, the model or variant and the date checked. When the manufacturer changes a specification, that record helps you update the affected cell instead of rewriting the whole page from memory.
For measured performance, include the test condition where it materially affects the result. “Up to” claims, laboratory figures and your own measurements should not be silently mixed. If you have not tested a product, do not write the table as if you have.
Read the finished table vertically as well as horizontally. Each column should describe one identifiable product; each row should compare the same attribute. Then ask someone unfamiliar with the products to explain the difference using only the table. Their hesitation often reveals an unclear unit more quickly than another round of promotional copy.