“挣”字:左边是手,右边是争。意思是你要用自己的双手去辛苦的劳动,才能争取获得一点报酬。
do you know the meaning of the left part of " 挣 ” ? It is a simbol of action/verb. In English, it is like " do / make". And the right part of the word is 争,争=strive for / fight for .
So, from the looking of " 挣 ” you know how difficult it is to 挣钱。
eg. This poor mother works hard in a factory to earn(挣) a living.
赚 : you can use this word when you earn money by buying stocks/lottery ,doing business or even by gambling.
there is something to do with luck. And it sounds happier if someone says " Oh, 我赚了500 USDs by buying stocks this month!"