What is the difference between metoprolol tartrate and the succinate?

They have the same ingredient, metoprolol, but in different forms (salts). While they are both beta blockers, they are not interchangeable and have different uses. They are not dose equivalent.
"Metoprolol tartrate is used to treat high blood pressure, chest pain due to heart disease, or heart attack. It’s also used to prevent heart attack in people who’ve had a heart attack or other heart disease.

Comparatively, metoprolol succinate is also used to treat high blood pressure and chest pain related to heart disease. It’s also used to treat heart failure. However, metoprolol succinate should not be used to prevent heart attacks." Source: healthline.