>>>>>Similarity? Maybe you should wear glasses. They are identical in Arial.
>>>>
>>>>One of the quirks of English is that similar can also mean identical, esp. in a scientific sense. e.g. "Prove these two triangles are similar" doesn't mean "they've both got 3 sides, for instance". That one has always bugged me.
>>>
>>>You had some sort of pox when they taught the definition of geometrical similarity? It means "they have the same angles in the same order, but not necessarily the lengths". That's maths, and the definition is unambiguous.
>>
>>Pox, Sir!? That's a bit heavy innit? I just used that as a top-of-the-head example. You're the mathmetician. And by "geometrical similarity" do you mean "congruity"?
>>
>If I'm not mistaken, these two terms are the same in Russian maths. However, I've tried to google congruity and could not find a good definition confirming, that similarity and congruity are the same.

They are not the same. Similarity means "sort of alike." Congruity means identical.