Code formatting is different with 4 spaces than 3 backticks

#1

Here is the same line of code twice, first enclosed in triple backticks (```) then with no backticks but instead four spaces at the beginning of the line:

/// MARK: Why is this not identical?
/// MARK: Why is this not identical?
(Tomáš Znamenáček) #2

I think it has to do with Discourse settings: