solution 是解决方法,有固定搭配如solution to/of,make solution,find solution
It may take a long time to find a solution to the problem.
也许要花很长时间才能找到解决这个问题的办法.
The solution of the problem is to take it away.
解决问题的方法是把它拿走.
而settlement一般没有solution这么常用,更偏重于解决
如the settlement of the problem,解释为问题的解决