Have a look at this: (http://ell.stackexchange.com/questions/44637/shore-shoreline-beach-coast-coastline). In short, oceans and seas have "coasts" or "shores"; lakes usually have shores, not coasts, unless they are very large. The coast extends inland a few km. The shore is the sandy (or gravelly) part directly adjoining the water (perhaps up to 100m - 300m inland). You might be able to buy a house on the coast, but not on the shore. The coastguard patrols the waters off a coast; there is no "shoreguard" (although there might be a lifeguard at the beach).

Both words have several meanings, but they share the meaning of "land at the edge of water". A coast is more broadly defined, and usually is adjacent to a large body of water like an ocean, a bay or a lake: - The West Coast of the U.S. has nicer weather than the East Coast. - The Mediterranean coast in Spain is popular with British tourists. - The coast (coastline) of Norway is rugged. A shore is the more immediate area next to a body of water: - Steer to boat towards the shore. - Their house is on the lake shore. The Jersey Shore is a popular vacation spot.

Both mean 'the edge of the land', but we use them in different contexts. We use the word 'coast' when we are talking about the land itself. 'On the coast' is the opposite of 'inland'. When we are talking about a particular country, we use the word 'coast' to talk about the parts of that country which are close to the sea. For example, Moscow is inland, but Vladivostok is on the coast. We use the word 'shore' when the context is water - 'shore' means 'land' when you are talking about the sea. We say 'shore' in contrast to the word 'sea'. For example, if you might say that the boat is sailing on the sea, close to the shore.