They're totally different things. Abstract is something that exists just as an idealized form. Eg. Abstract art, it is a form of expression but it's not an "accurate" depiction . It could also mean a summary in a research paper. Intangible is something you can't perceive with your senses. Eg. Love is a real thing but you can't touch it. I don't know if this makes sense, it's a little difficult try to explain it.