This is the single most consequential distinction in the category and the least clearly labelled.

What ground water actually does

Grass holds water low down even when the surface feels dry, and body weight presses the blanket into it. So the backing is not shedding rain from above; it is resisting water being squeezed up into it from below, continuously, under pressure.

That is a much harder job than a shower, which is why blankets that seem fine in light rain fail on a damp lawn on a sunny day.

What a bonded laminate does

A PU or TPU film laminated across the whole face is continuous and has no path through it. Water stays underneath for as long as you are sitting there.

Because it is bonded rather than loose, it also does not shift, bunch or trap water between layers.

What water-resistant usually means

A thin PEVA or PVC sheet, or a woven fabric with a light coating. Both slow water down and neither stops it under sustained pressure.

In practice that is roughly twenty minutes on genuinely damp ground, after which the blanket is holding the water against the person on it.

Why the label rarely tells you

Because there is no enforced definition of either word in this category, and both products photograph identically on a dry lawn.

The only reliable questions are what the film is and whether it is bonded. Both have short, checkable answers.

When water-resistant is the right buy

Indoor use, dry events, hampers, gifting, and anywhere the blanket is a decorative textile rather than a barrier.

It is a perfectly good product sold honestly. The problem is only ever the label.