Eruption

is a sudden outbreak of something; happens due to high pressures in the volcano

 


Source
https://simple.wikipedia.org/wiki/Plinian_eruption

lava

is a hot molton rock , flows out of the volcano either throuhg the top or sometimes it can escape from the sides. Forms rocks and islands when it cools 


Source
https://en.wikipedia.org/wiki/Lava_lake