Unterschied zwischen " und ' innerhalb HTML?

[suit]

Kann mir da jemand mal den Unterschied sagen?

3.2.2 Attributes
"By default, SGML requires that all attribute values be delimited using either double quotation marks (ASCII decimal 34) or single quotation marks (ASCII decimal 39). Single quote marks can be included within the attribute value when the value is delimited by double quote marks, and vice versa."