What is the difference between a process and a thread? ps -e -T | grep clementine

$ ps -e -T | grep clementine
  PID  SPID TTY          TIME CMD       # this is here for clarity
30046 30046 pts/2    00:00:17 clementine
30046 30049 pts/2    00:00:00 clementine
30046 30050 pts/2    00:00:00 clementine
30046 30051 pts/2    00:00:00 clementine
30046 30052 pts/2    00:00:00 clementine 

One way of looking at a process is that it is a way to group related resources together. A process has an address space containing program text and data, as well as other resources. These resource may include open files, child processes, pending alarms, signal handlers, accounting information, and more. By putting them together in the form of a process, they can be managed more easily. The other concept a process has is a thread of execution, usually shortened to just thread.

The thread has a program counter that keeps track of which instruc­tion to execute next. It has registers, which hold its current working variables. It has a stack, which contains the execution history, with one frame for each proce­dure called but not yet returned from. Although a thread must execute in some process, the thread and its process are different concepts and can be treated sepa­rately. Processes are used to group resources together; threads are the entities scheduled for execution on the CPU.

Further down he provides the following table:

Per process items             | Per thread items
------------------------------|-----------------
Address space                 | Program counter
Global variables              | Registers
Open files                    | Stack
Child processes               | State
Pending alarms                |
Signals and signal handlers   |
Accounting information        |