In one of my posts (Are "passive participle" and " Passive voice" the same in Modern English?), I said
I can't see the difference between ex_1 and ex_2.
Actually, I am not sure whether I used the right preposition. Another option could be "I don't"
I don't see the difference between ex_1 and ex_2.
Both "can't see the difference" and "don't see the difference" have some hits on ELL. I guess both of them are interchangeable in any situations.
Google Ngram also verifies this.
Is my understanding right?
Best Answer
Yes, your understanding is correct. "Don't see the difference" denotes you present state of not seeing, while "can't see the difference" denotes your inability to see.
In practice, they are interchangeable.
By the way, "can't" and "don't" are contractions of verbs with the word "not" ("can not" and "do not"). They aren't prepositions, that is, words like in, on, over, under, between etc.