what if Venus and mars switched places?

You'd have some very amazed planetary scientists....
Mars would be baked in the daytime, with 8 times the sunlight it's currently getting. Venus... that's interesting. It may have been almost comfortable to visit. The density of the atmosphere means there'd still be a greenhouse effect - so, I'm *guessing* it wouldn't be cold enough for the CO2 to turn to dry ice at the poles - but, imagine if there was... Venus, with polar ice caps of CO2 would have eliminated some (or maybe a lot) from it's atmosphere - reducing the pressure. Still not habitable for Man, but... it may have been a candidate for terraforming....

We would have a Red morning star. Not much else except Venus would become a planet in the Goldilocks zone and be worth trying to terraform.

Interesting question . But I don't have an answer . Mars would lose it's water .

Surface air temperature will average 68F = 20 c on Mars one century after the switch, with air pressure about double present. Warming will continue for several thousand years. Air pressure might peak at about 300 millibar, then decrease slowly. A few humans could sort of adapt to 300 millibars with just an oxygen mask. Most of us need 400 millibars minimum.
Venus would take about 1000 years to cool to average 20 c = 68 f, surface air temperature, but pressure would still be about 90,000 millibars, so we probably cannot build a space suit suitable for humans, on the surface of Venus. Worse, it would often rain sulphuric acid. The cloud tops would still be suitable for human colonies.

mars would heat up.
venus would cool off.

Mars will be be bombarded by a very stronger Solar wind, making it lose it's atmosphere at least 4x as faster.
Venus will enjoy less Solar wind, and less Sunlight to absorb (but will still be hotter than Earth).
Deimos will get heavy perturbation from Sun and will possibly escape.

Venus would be a bit colder, and mars would be hotter

it will b funny