There are 4 words: A, B, C, and D
A and B are synonymous verbs.
C and D are two letter words.
A C D and B C D are English phrases (mostly American) with opposite meaning from each other.
What are the words?
A is a verb and a noun. The verb involves using the noun. The noun in this case is quite a specific item.
B is a verb and a noun. The verb involves using the noun. A (the noun) sometimes has a B (the noun) and so B has come to mean using A very commonly. But it can be used more broadly.
A C D and B C D are expressions related to the effort someone puts into their work.