Technical Guides High-Frequency Welding vs Sewing for Waterproof Bags
A stitched seam is a row of holes. A welded seam is one piece of material. Which one your bag needs depends on what has to stay dry.
Technical Guides 
Technical Guides PVC or TPU? Choosing the Right Film for a Waterproof Phone Pouch
Both films are clear, both are welded, both take a logo. The difference shows up in the second season, in cold water, and on the invoice.
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