The Apollo GTS card would be fairly significantly faster then the Asus MX card.
However the Apollo card is likely a generic GTS made by a no-name manufacturer, compared to the MS made by Asus which is obviously well known.
The Asus MX card is likely more reliable and as higher quality components onboard, and possibly comes with a longer warranty.
Still, if you just want to save money then the Apollo card is probably fine, and the GTS is quite a bit faster then the MX.