Learn English – Proportion vs. portion

I already looked them up in dictionaries, but I can't understand the meanings completely.

They said:

• Proportion is a derived term of portion.
  As nouns the difference between proportion and portion is that proportion is (countable) a quantity of something that is part of the whole amount or number while portion is an allocated amount.
  As verbs the difference between proportion and portion is that proportion is (arts) to set or render in proportion while portion is to divide into amounts, as for allocation to specific purposes.

• As nouns the difference between ratio and proportion is that ratio is a number representing a comparison between two things while proportion is (countable) a quantity of something that is part of the whole amount or number.
  As a verb proportion is (arts) to set or render in proportion.

• As nouns the difference between portion and ratio is that portion is portion while ratio is reason.

I summarised them as the picture above.

According to the pie graph below (the previous question), I have been told differently that the words "ratio" and "proportion" don't suit the following sentence.

Overall, the numbers/percentages are not that very different for each _____.

However, as stated in my summary, thus "ratio" equals "percentage", and "proportion" is a quantity of something that is part of the whole amount. Now they should fit the sentence, shouldn't they?

What are the difference between:

1. proportion

2. portion

and

3. ratio?

Thank you very much :)