>>78 of course there is a difference. You may not ever have noticed but in 'Whitehouse' (the noun), normally white receives primary stress. In 'white house' (the adjective and noun combination), house receives stress [because of stress clash rules]. It does not seem like a large difference in isolation, but if someone were to speak without negotiating stress in this way (saying both words with stress), you would definitely notice the difference. To convince yourself of this, just listen to a Chinese learner of English who can pronounce all the phonemes right but does not know the tonal prosody of English.