Mars’s surface area nearly matches Earth’s dry land because of oceans
Mars, with a mean radius about 3,390 km (roughly half Earth’s), would cover about 28% of Earth’s surface (~145 million km^2); Earth’s total surface is ~510 million km^2, while its land area is ~149 million km^2. The near-equality arises because 71% of Earth is ocean, so Mars’s land area on a map looks close to Earth’s exposed land, even though Mars has no permanent oceans. The comparison is a scale exercise, not a claim that Mars is as large as Earth; Mars lacks oceans but bears evidence of past water in its terrain and contains surface/subsurface water ice.
