Different holiday companies "buy" different grades of room in hotels, so, yes, the "hotel experience" can be influenced by the tour operator's CHOICE of room standard.
Cheaper package holiday firms tend to "buy" the cheaper rooms in hotels, i.e. those without good/sea views, smaller rooms, rooms with fewer facilities, etc.
One of our worst holidays was to a 5* hotel in Kenya with Thomson (now Tui). Only two of the big tour operators used this particular hotel, being Thomson and Kuoni, and the Kuoni "package" was about twice the price. When we got there, we (and the rest of our transfer coach) were allocated rooms in one wing of the hotel. It was a real pit with threadbare carpets, luke warm water, faulty air con, etc. What we didn't know was that the other wing was newly modernised with all mod cons. Once when we were waiting at reception to complain (about no water at all that day), there was a Kuoni transfer coach arrived, and we noticed that they all walked away to the other wing. On departure day, we had to vacate our rooms about 12 hours before the transfer bus, so we were all offered use of an "open" room to have a wash etc - it was in the other wing. When we went over, we couldn't believe the much higher standard, all newly renovated, decent carpets/curtains, even brand new fluffy towels. We realised the difference in standard we'd have benefitted from had we gone with Kuoni!