Zen is a line of Buddhism. All Zen is Buddhism, but not all Buddhism is Zen. Zen comes from the term zazen, which is Japanese for meditation.
There are lots of Buddhist practices. Zen is the practice of realizing just what the Buddha realized, which is the way to stop suffering.
If you want to know Zen, study a mirror until you don’t know which side you are on. If you want to know Buddhism study the life of the Buddha.
Zen is fun because it has crazy methods to try to help you get beyond your thinking and feel the fundamental joy of life. Buddhism is fun because it teaches the same thing.
My teacher told me that if anybody asks me what Zen is, I should just hit the floor twice, thwat, thwat. If you get into a Zen practice, that could make a little sense.
All Buddhism teaches that life contains suffering, there is a cause of suffering, an end to suffering and there is a way to end suffering. Those are called the Four Noble Truths. The way to end suffering is the Eightfold Path, which is right speech, right thought, right livelihood, right intention, right action, right effort, right concentration and right view.
There are a billion ways to interpret what is right and how to follow the path.
The underlying idea is that we are something more than what we think we are. We are something less than we think we are. We are not what we think we are. We are exactly what we think we are. When we realize that, there is nothing to cause us suffering.