Hey!
Let's start with Australia and England:
- They both speak English as their main language
- They both have their cars steering on the right side
- They both have the Queen's head on the back of all coins
Next, Brazil and Portugal:
- Both have Portuguese as their national language
And thats pretty much all I have researched that they have in common
Last, Mexico and Spain:
- Both have Spanish as their national language
And thats all again otherwise they are very different.
Hope this helped!