Difference - Venus is extremely hot, Mars is like a cold desert 🌵.
Alike - You can see both with the unaided eye.
Difference - Mars is has two moons Venus has Zero.
Alike - They are both very close to earth 🌏.
Difference - Mars has 687 days in a year and Venus has 225 days in a year both (earthwise).
Alike - Both atmospheres have 95% Carbon Dioxide and 5% other materials (ex Nitrogen, Helium, & Oxygen etc.
Difference - There is a major difference in days 1,000 almost.
Alike - Both are very close to the sun.