A:AnswerAs Mark mentioned, I think you're thinking of the 2 memory sticks mentioned in the spec's. That's different than a SD memory card. The memory sticks are the memory inside the computer that it uses for running programs. It is an important spec for people who want to upgrade at some point so they know what memory configurations are available. It's also often more accurately described as "# of memory slots." In this case there are probably two 8Gb memory sticks inside this PC.
A:AnswerDell runs on Windows 11, the operating system different than Mac OS. Both have their own set of merits and features. You could purchase on according to your requirements and convenience.