@songkarn,
Sawasdii Khrap,
These definitions above give good distinctions between the two words. However, they are often used interchangeably in both speech, and writing. This is especially true of non-engineers. If you are in doubt as to what a new item you are workin on should be called, Google images of that item, and use the term you see listed most frequently.
Yin Dii Maak,
Dave
Thaidavid