Tree vs Graph

In this post, we will learn the difference between Tree and Graph in Java. This is a frequently asked
question in Java interviews for beginners. Let's dive into it.

Difference between Tree and Graph in Java

Tree Graph
A Tree is a special kind of graph where there are no cycles, i.e., it is acyclic. A Graph is a more general structure compared to a tree. It can contain any number of nodes (also called vertices) and edges, including cycles.
In a tree, there is always a unique path from the root node to any other node. In a graph, there can be multiple paths between two nodes.
Trees have a hierarchical structure with a definite parent-child relationship. Graphs may not necessarily have a hierarchical structure and can have complex relationships.
All trees are connected and they always have a root node. Graphs can be disconnected and they do not necessarily have a root node.
A tree has N-1 edges where N is the number of nodes. In a graph, there is no such relationship between the number of edges and vertices.
Trees do not contain self-loops. Graphs may contain self-loops (an edge that connects a vertex to itself).
A tree is an undirected graph. A graph can be either directed (edges have direction) or undirected.
A tree has a clear flow of control from top to bottom. Graphs do not have a clear flow of control, the control can traverse any path.
Trees are used in areas like hierarchy representation, XML/HTML parsing, routing algorithms etc. Graphs are used in areas like social networks, web page link mapping, location/routing algorithms etc.