Engine fan coupling on '05 Durango 4.7L vs. '05 Jeep 4.7L

The mechanical engine fan is very noisy on startup in my '05 Durango 4.7L -- sounds like a hurricane on startup and takes a minute to quiet down. I
realize this is normal and why it happens.
But the same fan in my '05 Grand Cherokee 4.7L is very quiet on startup! As if it doesn't have the same kind of ordinary viscous coupling that the Durango has.
Does anyone know why? Perhaps the Jeep may have an electrically operated clutch of some kind?
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