The difference between using Gerund and Abstract Noun is "the way to use it".
It is true that Gerund is a form of adding -ing to a verb to form a word to "be just like" a noun.
For example, arrive (V) --> arriving (N) ? (How about "arrival (N)" ?)
As it has been said Gerund is formed to be like a noun, it can, in fact, a noun and sometimes an adjective.
For instance, consider the following sentences
- I have to clean the room because of your arriving. (Incorrect)
- I have to clean the room because of your arrival. (Correct)
Roughly, it seems fine for both but you have known "arrival" is a noun. Why do you have to use "arriving"? When would "arriving" be used?
Let's see another example.
- Peter ran quickly for arriving at the classroom on time. (Correct)
- Peter ran quickly for arrival at the classroom on time. (Incorrect)
Since a noun is meant to be after "for (Preposition)", "arrival" could have been reasonable enough to be put there.
Yet the noun "arrival" cannot have anything after it. Therefore, if something has to be after the word, Gerund form of it is supposed to be used.
Likewise, any other nouns, too, follow the rule depicted above such as disposing (disposal), proposing (proposal), etc.