Heap Based Classes and Garbage Collection

In Java objects are created on the heap using the new keyword. Most classes in C# are created on the heap by using the new keyword. Also just as the JVM manages the destruction of objects so also does the CLR via a Mark and Compact garbage collection algorithm

NOTE: C# also supports stack-based classes, called value types.

Of Virtual Machines and Language Runtimes

Just like Java is typically compiled to Java byte code which then runs in managed execution environment (the Java Virtual Machine or JVM) so also is C# code compiled to an Intermediate Language (IL) which then runs in the Common Language Runtime (CLR). Both platforms support native compilation via Just In Time compilers.

NOTE: While the Java platform supports interpretation of byte code or byte code being JITed then run natively, the .NET platform only supports native execution of C# code because the IL code is always natively compiled before running.