There is a difference between shade houses and green houses.
I would explain it as, shade houses use shade cloth as a covering and green houses can use glass or other solid coverings, which give more protection and warmth during the winter season.
The very informative article below is taken from Garden Action website, and gives some more details on shade houses and green houses.
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As gardeners, we understand the importance of light and temperature to growth. Flowering plants and vegetables are best grown in as sunny a place as possible for the best results. We use glasshouses to this end, using materials that transfer light with as little hindrance as possible. To non gardener, it may be difficult to imagine why we should construct a shadehouse to reduce light.
Advantages
In high summer, the amount of light falling on plants may be much more than is needed for growth. High light levels contribute to the development of leaf colour and flowering, though in many cases, excessive light can be harmful. A shadehouse allows a balance of the amount a plant receives with the amount it needs. Reduced light levels in summer slow plant processes so that less watering is needed. High temperatures and intense light can damage some plants. Seedlings benefit from a few days in the shadehouse to harden off before before planting outside.
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To read the full article head over to Garden Action website.