Entravision was formed over 30 years ago by a former GM of KMEX (TV) in LA and an investor. It was set up with the backing of Univision to own TV stations in markets smaller than the top 7 that Univision was limited to at the time.
Later, Entravision added radio to support and promote their Univision TV affiliates.
Today, TelevisaUnivision owns 10% of Entravision. TelevisiaUnivision is not the "parent" of Entravision. Univision does not even have a seat on Entravision's board.
The two companies do not share operations in any way, and are competitive against each other in several radio markets, like Phoenix and Las Vegas where they have direct same-format competitors.
Of course, Univision is getting out of Las Vegas entirely with its recently approved sale, mostly because Las Vegas has turned into a terrible and unprofitable radio market with 91 radio stations, including the translators. In 2016 the market had billings of $69 million, and now it is less than $52 million.