Often yes, but only if you treat it as one elastic specification applied to two patterns, not one waistband that is assumed to fit both. The elastic tape can be shared. The finished waistband length, how it is joined to the body fabric, and the stretch the garment needs at the waist are style decisions. They still need to be set and approved per style.

Specify the elastic, not just the look

A branded jacquard waistband is usually ordered by width, colour and logo artwork. That describes the appearance. For performance, the elastic needs measurable properties. ASTM D4964 is a common method for elastic fabrics: a loop specimen is cycled on a constant-rate-of-extension tensile tester, and tension at an agreed elongation, or elongation at an agreed tension, is read from the third cycle. The standard leaves those points to agreement between buyer and supplier, so put them in writing.

With one tested elastic reference, both styles draw from the same approved tape. Lot-to-lot changes can then be checked against numbers rather than feel.

What still differs between boxer briefs and trunks

Trunks and boxer briefs usually differ in rise and leg length, and may differ in body fabric. The finished waistband length for each size comes from that style's pattern and the stretch you want at the waist. A shared tape with the wrong cut length will feel tight on one style and loose on the other. Ask the factory for a waistband length chart per style and size, and approve fit samples of both styles in the same elastic.

Check it after washing

Waistband complaints often appear after laundering, not on the first wear. ASTM D4964 notes that the laundering temperature and the number of wash and dry cycles must be agreed. You can use a named procedure such as ISO 6330 and re-test the elastic after the agreed cycles. Doing that once on the shared tape covers both styles, which is part of the saving.

So the answer is to share the elastic specification and its test results, and keep the cut lengths, joins and fit approvals style-specific.

Keep the tested elastic reference and both styles' waistband charts in the same tech pack, so a reorder or a new size cannot drift away from what was approved.