ほぼ and ほとんど: What's the difference and how do you use them?


What is the difference between ほぼ and ほとんど?

They both mean almost, don't they? Can they both be used in both positive and
negative?




I'm Japanese and I could not figure out the difference by myself. But after I
googled it and read the answer, I was convinced of the difference. I realized
that I have been using each word on a case-by-case basis.

Well, only about ほとんど, you have to care about the use cases, whereas you can
use ほぼ in every cases which means "almost" or "about".  
You could use ほとんど only when the goal is clear or the max is 100% or the
minimum is 0%. For example, you could say "宿題は、ほとんど終わった" but you could not say
"学校まで歩いてほとんど１時間かかる".

With the phrase of "宿題は、ほとんど終わった", the goal is clear. The goal is finishing
the homework. But with the phrase of "学校まで歩いてほとんど1時間かかる" there is no goal and
neither its max. It just takes about an hour. That's all. In the both of these
two cases, you could use "ほぼ" like "ほぼ終わった" or "ほぼ1時間かかる".

”プールの中の水は、ほとんど満杯である” = Good  
Because there is the max. The max is fully filled water.

"プールの中の水は、ほとんど1000mlである" = Bad  
It just says, it is 1000ml. It doesn't say about the goal.

~~By the way, they both can be used in both positive and negative.~~ Read
@ちょこれーと's answer about this.

