What is difference between "You did a hard work" and "You worked a lot" ?
Is there a significant difference between meanings?
I can not understand correct meaning, because english is my second language.
You did hard work.
or more naturally,
You worked hard.
says that the person put a lot of effort into the work. The former implies that the nature of the work is difficult, while the latter implies that the worker was very diligent in applying high effort. If you say
You worked a lot.
then you are saying that the person put a lot of time into their work, but are not necessarily implying that a lot of effort was required at any given time.
Use of the indefinite article "a" with "work" is archaic, I think. I see this usage in scriptural texts but not normally in conversation nor contemporary writing. Here "work" takes on the meaning of something that is coming about, rather than the effort taken by the workers.
Therefore, behold, I will proceed to do a marvellous work among this people, even a marvellous work and a wonder: for the wisdom of their wise men shall perish, and the understanding of their prudent men shall be hid.
That's archaic language from the King James Version of the Bible.