Product placement in video productions : media exposure of your product leading to increased awareness and sales.
Giving product to high visibility people : media exposure of your product leading to increased awareness and sales.
Not much difference at all as I see it.
Of course, for this to work well. The media exposure must be positive.
So, you must not give it to a personality that may embarrass you. You have a bit less control on those high profile people, and how the message gets out, than when going through traditional media. But, the upside is a lot more powerfull than merely seeing the product in a media. Nike built 10B in sales on the name of Jordan alone.
The personalities own Brand, style, identity and credibility also sells the product. When the product is highly related to the personalities area of expertise (like a fashion icon (Turlington, Lagarfeld) wearing your product (or Jordan wearing shoes), this effect is amplified).
Apple has used media exposure of their products for 25 years at least, this is the same thing except with a personal product like clothing, you use something a bit different than merely showing the tech.