You can’t compare apples and oranges
Definition 1 of 1
Pro Tip 1/3Context Matters
Use the phrase when discussing items that don't share enough qualities for a fair comparison. 
Chuck weighs 50kg and Linda lifts weights. You can't compare apples and oranges.
Pro Tip 2/3Avoid Confusion
Don't use the phrase if you're actually talking about fruit. It's a metaphor for dissimilar items. 
Soccer and ballet require different skills; you can't compare apples and oranges.
Pro Tip 3/3Imagine Variety
Picture vastly different items or ideas to understand 'apples and oranges' as symbols of diversity. 
It's sunny and he's cheerful, but you can't compare apples and oranges.