1. Heavy weight components are always Rectangle in shape
while light weight may or may not.

2. Heavy weight components borrows the native screen to
paint their components while light weight render their
components by their own screen painting APIs.

3. They differ from z-indexing to each other, heavy weight
components are always displayed at the top of all
lightweight components.

4. Light weight components are faster in response and
performance.

2, light weight components borrows the native screen to
paint their components while Heavy weight render their
components by their own screen painting APIs.

[Short answer: threads are lightweight, programs (aka
processes or tasks) are heavyweight. -Alex]

Lightweight and heavyweight processes refer the mechanics of
a multi-processing system.

In a lightweight process, threads are used to divvy up the
workload. Here you would see one process executing in the OS
(for this application or service.) This process would posess
1 or more threads. Each of the threads in this process
shares the same address space. Because threads share their
address space, communication between the threads is simple
and efficient. Each thread could be compared to a process in
a heavyweight scenario.

In a heavyweight process, new processes are created to
perform the work in parallel. Here (for the same application
or service), you would see multiple processes running. Each
heavyweight process contains its own address space.
Communication between these processes would involve
additional communications mechanisms such as sockets or pipes.

The benefits of a lightweight process come from the
conservation of resources. Since threads use the same code
section, data section and OS resources, less overall
resources are used. The drawback is now you have to ensure
your system is thread-safe. You have to make sure the
threads don't step on each other. Fortunately, Java provides
the necessary tools to allow you to do this.