Curt usually refers specifically to speech, while brusque is more general, referring to manner and behavior as well as speech. Also, a "curt reply" is a bit more rude than a brusque one.
These two words have a large semantic overlap, but at the edges there are a few key differences.
Electric is used to describe things pertaining to electricity. It can also be used metaphorically: "the evening was electric".
Electrical can be used nearly everywhere that electric is used when pertaining to electricity (aside from some set phrases). It is not generally used metaphorically in the way electric is. The word electrical can also be used in an additional domain: things concerning electricity. So, generally, people do not say "electric engineer" unless the engineer runs on electricity; instead they say "electrical engineer".
So, in the case of "electric(al) machine" from your question, since you are talking about something that runs on electricity, the two words are essentially identical in meaning.
Different is the broadest and most vague expression of difference, but generally it means a difference of a quality of two or more things. "They were of different __"
Divergent suggests two things which are "moving" but apart from each other. "They had divergent philosophies on the importance of the State."
Disparate tends to suggest quite a wide gap. Often in the context of things scattered, or quite far apart. Incomparable. "They had disparate views on the necessity of cinema."
Distinct merely indicates that two qualities or objects are not the same. They may be "similar, but distinct" or they may be "quite distinct" (i.e. you'd have to be a moron to not notice the difference).
Each has a correct usage. When in doubt go for "difference". It covers most of the ground and there's no point in using a big word if you have to ask about it.
Best Answer
Curt usually refers specifically to speech, while brusque is more general, referring to manner and behavior as well as speech. Also, a "curt reply" is a bit more rude than a brusque one.