Java is a high-level programming language originally developed by Sun Microsystems and released in 1995. Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX.
.NET framework is a computer software framework invented by Microsoft. It runs on Microsoft Windows OS (Operating Systems). It provides user interface, data access, database connectivity, cryptography, web application development, etc.
Java supports only Java patterns.
.NET supports multiple languages such as VB.NET, C#, F#, etc.
Java is platform independent and it can run on Windows, Linux and Mac OS.
.NET works on Windows.
Java has Java Virtual Machine, ByteCode, JDK, JRE, etc.
.NET has Common Language Runtime
Java has Java Beans, whereas .NET has its classes.
JDBC is used for connecting Java with database, whereas for database in .NET, use ADO.NET.