I believe there is a distinction, but it is largely one of tradition, and not of affect.
Saints, when referred to with a capital “S”, are generally those individuals that have been officially cannonized by the Catholic Church. the capitalization, I believe is merely a nuance of language, as Saint Monica is a proper noun, just as Mr. Jones is a proper noun. I have seen the word Saints capitalized, I believe, but it is always in reference to the collective of offically cannonized people.
We are all called to be saints, and there are many many saints who are not officially cannonized.
With that being said, there is no difference between saints that have been officially declared by the Church and those who have not. Anyone who has achieved salvation and is with God in heaven is a saint, and there are obviously way more souls in heaven than just the small list of people the Church has officially cannonized.
The powers most often associated with cannonized saints is probably just because one of the criteria for cannonization is a verifiable miracle. There is nothing in Church teaching that lends a miracle of God to be exclusively delegated to the list of Saints. God works miracles, big and small, every day, and I am sure that most of them we will never know about.