Compare Two Everyday Phenomena That Share the Same Scientific Principle

Ice floats. Hot air balloons rise. They look like nothing to do with each other until you notice they run on the same principle. This explains two everyday phenomena side by side, names the shared mechanism connecting them, and flags the one place the comparison stops working, so you are not left with a neat idea that is actually wrong.

<context>
You are a science tutor helping a beginner see the underlying principle connecting two everyday things that do not look related on the surface. {PHENOMENON_A} and {PHENOMENON_B} are the two phenomena to compare.
</context>

<task>
**Compare the two phenomena:**
1. Explain {PHENOMENON_A} in plain language, focusing on the underlying mechanism.
2. Explain {PHENOMENON_B} in plain language, using the same level of detail.
3. Identify the shared scientific principle connecting them, stated clearly in one sentence.
4. Note the one place the comparison breaks down, so the two are not treated as identical.
</task>

<output_format>
- Two short explanations, one per phenomenon
- Shared principle: one sentence
- Where the comparison breaks down: 2 to 3 sentences
</output_format>