1. Neo4j ：
Neo4j 是最著名的图形数据库管理系统，它也是 Neo4j, Inc. 开发的 NoSQL 数据库系统。它不同于 Mysql 或 MongoDB，因为它具有与其他数据库管理系统相比的特殊功能。
Neo4j 还以图表的形式存储和呈现数据，而不是表格格式或 Jason 格式。在这种情况下，整个数据由节点表示，在那里您可以创建节点之间的关系，这意味着整个数据库集合将看起来像一个图形，这使得 Neo4j 与其他数据库管理系统不同。
2. PostgreSQL :
PostgreSQL 是一个开源的、功能非常强大的对象关系型数据库系统。它使用并扩展了 SQL 语言，并结合了许多存储和扩展最复杂数据工作负载的功能。 PostgreSQL 的功能包括帮助管理员保护数据完整性，开发人员构建应用程序和构建容错环境，并帮助管理我们的数据，无论数据集大小。
作为开源软件，其源代码在 PostgreSQL 许可下可用，这是一种自由开源许可。 PostgreSQL 也称为 Postgres，由加州大学伯克利分校的 Michael Stonebraker 开发。
Neo4j 和 PostgreSQL 的区别：
| S.No. | Neo4j | PostgreSQL |
|---|---|---|
| 1. | It was developed by Neo4j, Inc. | It was developed by Global Development Group. |
| 2. | It was initially released in 2007. | It was initially released in 1989. |
| 3. | It is written using Java and Scala language. | It is written using C language. |
| 4. | Neo4j server operating systems are Linux, OS X, Solaris, and Windows. | Its server operating systems are Free BSD, HP-UX, Linux, NetBSD, OpenBSD OS X, Solaris, Unix and Windows. |
| 5. | Neo4j APIs and other access methods includes Bolt protocol, Cypher query language, Java API, Neo4j-OGM, RESTful HTTP, API, Spring Data Neo4j, TinkerPop 3. | APIs and other access methods include ADO.NET, JDBC, native C library, ODBC, streaming API for large objects. |
| 6. | It does not support SQL. | It supports SQL. |
| 7. | Its primary database model is is Graph DBMS. | Its primary database model is Relational DBMS. |
| 8. | Neo4j supports programming languages which are .Net, Clojure, Elixir, Go, Groovy, Haskell, Java, JavaScript, Perl, PHP, Python, Ruby and Scala. | It supports .Net, C, C++, Delphi, Java, JavaScript (Node.js), Perl, PHP, Python and Tcl programming language. |
| 9. | Neo4j is uesd by famous companies like medium.com., Stack, Fiverr, Fundamentei, Trendyol Group, double slash, ingsmen Software, GAPO, etc. | Famous companies like Apple, Macworld, Debian, BioPharm, Etsy, Fujitsu, Red Hat, Sun Microsystem, Skype, etc uses PostgreSQL. |