Museum and gallery(museum gallery heritage)

The main difference between art galleries and museums is that museums displays the art and only for viewing. While galleries also shows art but also sells the art to interested and wealthy individuals.

MUSEUMS

Art museums are building that collect, preserve and research objects of historical, scientific and artistic value
as well as provide social and educational services. Museums collect and care these objects for their value and making them view able to the public. Museums are said to be able to 'bring the past  to life' as they show different periods of our history. They also enable visitors to feel and see the past through this objects.

Museums are mostly free of charge and free to be viewed in public. This is because most museums are funded by the government, foundations and donors that generously donate and support the museum without profit.

GALLERY

Like Art museums, Galleries also shows art to the public but the main difference is that they also sell the artwork in auctions to interested buyers especially artist. Although some galleries do no charge any admission fees but they encourage people to view and buy their work. Artworks within the gallery are not permanently kept.

HERITAGE

Heritage is a range of objects, traditions and cultures that we have inherited and were passed down from our ancestors. Songs, recipes, dances and many others elements that are inherited by us that we use to identify us and our culture.  

Reference
http://www.quora.com/What-is-the-difference-between-an-art-gallery-and-museum
http://en.wikipedia.org/wiki/Art_museum
http://www.leeds.gov.uk/museumsandgalleries/Release%20Documents/AM%20what%20is%20a%20museum.pdf
http://familysearch.org/learn/wiki/en/What_Is_Heritage%3F
http://www.umass.edu/chs/about/whatisheritage.html