The similar word that looks like each other

I have not understand any word that it means what.
example, Multithread,Multiprocess and Multitask any others.
So, They are very similar! I mistake often.
I list the meaning each word, I will not make a mistake more.


It is produced some by application that named thread.
Thread processes self task and same time another Threads is doing.
This is achieved because they use very short time what CPU had allocated processing time for them.
It looks like some thread is running same time. 


It is similar to Multithread.
Multithread is event under application and Multiprocess is event under OS.
OS allocates CPU processing time for application.
If you will run many application will delay run time of it.


It is the same meaning of Multiprocess. 

・Parallel processing

This will allocate for microprocessor processing.
If one computer has multi microprocessor, They is allocated something task, example calculation.
You will be able to improve processing time of computer of system. or software and programming technique that you uses such an environment

I bring these together,

Multithread is event under application. Multiprocess is event under OS. Parallel processing is layer of hard ware.