by making it so that it is hidden to anyone, except for google. It is not possible to hide your ip completely online. Your ip address is the only way for anyone to reach you. The only way to hide your ip from someone is to have someone else (who does know your ip address) make the request on your behalf, and forward data forward and back between the two endpoints. Everything has to go through the middleman.
It's a Google VPN, which means they own it, which means they see literally everything you do if you use it, rather than just seeing what you do if you visit a page with their tracking and you don't block their cookies and scripts.
The difference is that those companies presumably don't run the biggest advertising agency in the world, don't cooperate with governments, and don't log your history or original IP address. Using Google as a VPN provider in oppressive countries that punish free speech online could present a serious hazard. Plus there's just the overall privacy issue too.