Not sure why you are asking this point, as applies to all hotels and brands. Typically whether booking standard/superior/deluxe room type etc, within each room bracket you usually see different bed types eg a)deluxe room twin beds b)deluxe room queen bed d)deluxe room king bed e)deluxe room + in some countries a smoking/non-smoking room set per roomtype.

Usually if you expand a plain 'deluxe room' it will say something along the lines
'Deluxe Room Type Allocated on arrival, your bed and smoking preferences can not be guaranteed'.

I always choose rooms 'Bed Type' I want at booking time if available, but if only my non-preferred 'bed type' showing I choose deluxe and hope I get the non-showing other room beds type at checkin time