The difference often shows up in patterns. When someone is overwhelmed, they may try to get tasks done in principle—but they signal too late that time, resources, or priorities aren’t sufficient. With genuine unreliability, commitments are made casually, feedback doesn’t come through, and responsibility is explained rather than taken on.
Look at three points: First, whether problems are raised early. Second, whether the employee proactively offers solutions. Third, whether behavior improves after clear agreements. When someone is overwhelmed, they often feel relieved when there is structure and prioritization. When someone is unreliable, they’re more likely to evade, downplay, or shift responsibility to others.
For your conversation, that means: Don’t label too quickly. Instead, use examples, follow-up questions, and clear commitments to check what’s really behind the behavior.