The Park Hyatt and the Westin are in the same street, so answer is the same : the Roissybus will drop / pick you at / from the Opera, which is walking distance from either hotel. As a matter of consequence, the Roissybus is offering you the only non-stop, direct transportation mean.

Now, I wonder...unless you're staying on an award stay, why not go for a taxi that will cost about a tenth of a night stay in either property ?