I've checked and deciphered the codes that you can get from turning the ignition switch on & off with the check engine light, but my question is - are these the same identical codes that you'll get by checking with a code scanner? Or does the scanner give additional info/details?

 

Depends on the scanner the better one will tell you what each code means the cheaper one gives only the code and yes they will be the same codes you get off the ign switch.