If I add a backslash+space to the start of double and single quoted strings, I get different results:
I'd refer you to "Ruby Programming/Strings" for a very concise yet comprehensive overview of the differences.
From the reference:
puts "Betty's pie shop"
puts 'Betty\'s pie shop'
Because "Betty's" contains an apostrophe, which is the same character as the single quote, in the second line we need to use a backslash to escape the apostrophe so that Ruby understands that the apostrophe is in the string literal instead of marking the end of the string literal. The backslash followed by the single quote is called an escape sequence.