Wikipedia:

Scrambling is accomplished by the addition of components to the original signal or the changing of some important component of the original signal in order to make extraction of the original signal difficult.

Whereas encryption usually refers to operations carried out in the digital domain , scrambling usually refers to operations carried out in the analog domain .

In telecommunications, a scrambler is a device that transposes or inverts signals or otherwise encodes a message at the senders side to make the message unintelligible at a receiver not equipped with an appropriately set descrambling device

https://en.wikipedia.org/wiki/Scrambler