Hmm... You mean the Orchard Hotel at the junction of Orchard Road and Orange Grove Road right?

It's 4-star for a start, compared to MM which is 5-star. MM also just completed a refurbishment, so am not sure whether you are referring to the MM of old, or the refurbished one. To be honest, I have never seen the rooms of the Orchard hotel so can't really comment on them. Though they do have a nice buffet in one of their restaurants. The foyer certainly doesn't look at grand as the MM.

Location-wise, they are both about 10 minutes walk from the closest MRT location. The Orchard Hotel is along Orchard Road, but it is right at the end of the road, so would probably need about a 5-10 minute walk to where the action is along Orchard Road. Given the choice, I would actually go for MM juz for the location alone. The MM provide pretty decent views of the Singapore skyline; u probably see nothing in Orchard.

Here's my take on it. Hope it helps!