Most likely, the actual performer makes tons more money than the actual songwriter because the actual performer is well known and makes money by singing. However, the songwriter could make a large amount of money, but it would most likely not exceed that of the actual performer. If you want to make money as a songwriter, it is important to have a background in music.
Then you can learn to write music. When you are trying to write a hit song, consider the hook. This is the most important part of the song that most people remember. It would be the catchy part. The hook will be the actual words and not the music in that song. The hook can be the chorus that is sung.
Sometimes song writers will make more money than the actual musical performer, but it really depends on the song writer and the performer. There are some really famous song writers who may charge a fee for writing a song or collect a certain percentage of the revenue from a song when it is successful.
Some musicians will make more money than the song writers though, especially if the musician is well known and the song writer is not as well known.