黑幕 (hēimù) vs. 内幕 (nèimù): This is a critical distinction.
内幕 (nèimù) means “inside story.” It is a neutral term. A company's secret product development plan is a
内幕, but it's not necessarily corrupt.
黑幕 is a specific *type* of
内幕—one that is dark, illegal, or unethical. All
黑幕 are
内幕, but not all
内幕 are
黑幕.