Matthew & Levi: The Same Guy!

I read in the book of Matthew where the tax collector that Jesus told to come "follow Me" was called "Matthew", but in the book of Mark, the same guy was referred to as "Levi".

I wondered, "Why does he have two different names?".

Matthew is the Greek name and Levi was the Hebrew name. As a tax collector, Matthew worked for Greek-speaking Romans. He gathered taxes from Hebrew-speaking Jews. We see, as an example, Peter also being called Simon (Matt. 16:16).