CONDITION is the state of something, especially with regards to its appearance, quality or working order and a SITUATION is a circumstance in which one find himself or herself in. I hope this helps you.

Condition is used to describe something tangible-you can see or touch it. Situation is used to describe something like an event or circumstance. These words are not generally interchangeable. For example I could say "the condition of this house is a mess" But it would sound weird to say "the situation of this house is a mess." (Although I would understand what you meant) But I could say "the messy house is a situation we need to fix." Now I'm referring to the circumstance of the house being messy.