No candidate, on either side, ever talks on substantive issues in any detail. Quite frankly, if they did the viewers' eyes would glaze over and they wouldn't have a clue as to what's being said.
Candidates can only keep voters' short-attention spans engaged with broad strokes, high level points. In Trump's case those points include things like "vetting refugees flooding in from Muslim countries", "building a wall on the southern border", "repealing Obamacare and taking steps to fix the health insurance situation", "fixing trade deals to help American companies", "reversing course on being so P.C. that we can't function", and so on. See his site for detailed discussions.
Hillary simply rattles off poll-tested talking points, and has no real plans. Cruz isn't much better in that regard... he won't stop illegals, he won't dare prevent Muslim terrorists from flooding in, and changes to Obamacare will be in favor of his big donors in the industry, etc.
Apparently, Sanders has no idea how he will break up the banks, claims 10,000 innocent Arabs in Gaza have been kill by Israel without any factual basis he can cite to, and has no idea what Israel should do differently.
Trump’s problem is that his positions are all over the chart. Abortion is a classic example.