Process and a thread

1) What is the difference between a process and a thread?

2) What is a process image?

3) What was the reason for splitting the "suspend" state into blocked-suspend and ready-suspend states?

Chapter 4

4) How can threads be used to speed up execution?

5) Why do thread activities sometimes require coordinating?

6) In user level threads, a system call by a thread may block all other threads of the process. Explain why.