On Venus the surface temperature is hot enough to melt lead, the atmospheric pressure is so great it’s equivalent to being under 3,000 feet of water and it rains sulfuric acid. Any probe landed there, no matter how strongly it’s built, will fail after a short while. The Russians knew this so they built some really strong probes and took as many pictures as possible knowing the thing would die after a few minutes. It’s the only reason we have any photos from the surface of Venus at all.

On Mars, we can land a probe and take our time to make sure everything is working correctly because although Mars is harsh to humans, a probe does okay during the daytime hours on the Martian surface even though it gets really cold at night.