What golden hour is
When the sun is low, between about 6° above the horizon and 4° below it, its light travels through more air: it's warmer, softer, and casts long shadows. That's golden hour. Its length depends on where you are and the time of year: shorter near the equator, longer further north and in winter.
What blue hour is
Once the sun is between about 4° and 6° below the horizon, the sky turns deep blue and lights in windows and streets balance with it. It's short, often 20 minutes or less, so be set up before it starts.
Shooting a house
For exteriors, shoot the front of a house in the golden hour when the light falls on it, and twilight shots in the blue hour with the interior lights on. Shade Map shows which side of a house the sun is on at any hour, and where the shadows of its trees will fall.