Area and perimeter sound similar and use the same rectangle, so people blur them together. They measure completely different things.
Two Different Questions
Area asks how much space is inside — the squares that fill it. You'd care about area when buying carpet, paint, or turf. It's measured in square units. Perimeter asks how far is it around the edge — the fence, the skirting board, the trim. It's measured in plain units of length. In the toy, "area" lights up the inside; "perimeter" traces the border.
The Proof They're Unrelated
Press "surprise me". You'll see two rectangles with the same perimeter but different areas — a 2×6 and a 4×4 both have a perimeter of 16, yet one holds 12 squares and the other 16. So knowing one tells you nothing certain about the other. They are genuinely separate ideas.
The Units Giveaway
If you're ever unsure which you've found, look at the units. A "squared" unit (cm², m²) means you've got area. A plain unit (cm, m) means perimeter. The little ² is doing real work — it's telling you that you multiplied two lengths together to cover a 2-D space.