Basics Of Voice Recognition for a Project Help

I am making a project which is related to Voice/Speech Recognition and i need your help. Thank you for reading.
What I really want to know:
1. Is there any difference between Voice Recognition and Speech Recognition?
2. What are the pre-requisite subjects should i take before going through the field of Voice/Speech Recognition?
3. What is the average cost making a simple Voice/Speech Recognition? In any currency.

If you can help me in my project, it would be better. Im planning to make a simple Voice/Speech Recognition device that can "memorize" 2 words (ON and OFF) that is connected to a LOCK. but if I said "ON" in a low voice, it would not take any orders. But if I shout "ON" then the lock will be release. Just simply that. (i dont know if its easy to make).

Sorry for wrong grammars btw. Thank you, any replies will be appreciated.

SALAM
i am also Working on voice recognization and i am using the co-relation technique to recognize FIVE different Words. pre-requisite subjects is DSP but in this project i found all things from GOOGLE . . . .
In my Project i first understand the CODE for Voice recognizatoion and then implement my own CODE and you should have some knowledge about MATLAB FUNCTIONS related to sound
may it help you :roll: