A volcano is a mountain that is generally formed from the out pourings of lava/magma.
Let's take the magma lava thing first. Magma is molten (melted) rock. There are a few ways to create magma, but the easiest explanation is a combination of high heat and low pressure. The heat is usually several thousand degrees, but low pressure is needed because solid rock needs room to expand and melt into. Too much pressure keeps that melting point even higher.
Lava is the exact same thing as magma, except instead of being inside the Earth, it has erupted/flowed out onto Earth's surface.
As rock melts, and turns into magma, it expands; therefore, it becomes less dense. This lower density caused the magma to rise toward the surface of the Earth. The magma can create a bulge on the surface of the Earth. That's an early volcano. The magma will eventually find a way to Earth's surface through cracks/vents and begin pouring out. That's a shield volcano. It tends to be wide and not steep. Mauna Kea in Hawaii is an example.
The magma can be silica rich magma which makes it thick and slow moving. That plugs vents and creates an explosive eruption. The volcano will erupt a lot of pyroclastic material instead of lava. Ash and rock in other words. This type of volcano is a cinder cone volcano and tends to be steep sided. Pericutin in Mexico is a good example.
The last kind of volcano is a composite/stratovolcano, which is a combination of the first two. Something like Mt. Fuji in Japan. These volcanoes will first erupt explosively to clear the vents and then have large outpourings of lava.
A volcano is defined as a rupture on the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
Magma is the molten rock contained in the volcano, when the volcano erupts and magma comes out it is called lava. Basically the only difference between magma and lava is that magma is inside the volcano while lava is outside.
A volcano, put in simple words, it similar to a mountain. But it has a large hole on the top of it, where magma comes out and turn into lava. Magma is the molten rock that it contained underneath the Earth's crust. When this magma comes out of volcanos onto the Earth's surface, then it is called lava. Volcanos can be either on land or in the sea, and are formed after thousands of years.
A Volcano is a mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust. Lava is hot molten or semifluid rock erupted from a volcano or fissure, or solid rock resulting from cooling of this. Magma is hot fluid or semifluid material below or within the earth's crust from which lava and other igneous rock is formed by cooling. Magma and Lava are different.