What matters for a utility patent?
Start with each asserted claim, not the patent's general objective. A product can solve the same problem through different features. Conversely, a different product name or overall concept does not establish that a claim limitation is absent. Record the technical evidence supporting each part of the comparison.
What if a claim limitation is not literally met?
The doctrine of equivalents may require a further comparison. Warner-Jenkinson Co. v. Hilton Davis Chemical Co. requires an element-by-element inquiry and does not permit equivalence to eliminate a claim element. Prosecution history can also limit the available equivalents under Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.
What if the patent is a design patent?
Egyptian Goddess, Inc. v. Swisa, Inc. applies the ordinary-observer test, with the prior art informing the comparison where appropriate. Analyze the patented design and accused appearance; a utility claim chart alone does not answer that question.
What should I give counsel?
Provide the patent, the actual product version, drawings, photographs, and an explanation of the material differences. Ask which differences matter under the relevant claims and infringement test.