Textbook Questions/Access code mess

I decided to go book-less this entire semester, and so far I’m doing alright. However, one of my classes require a textbook that comes with an access code which holds all the online work I have to do and my professor grades the class homework.
I copied the ISBN and found the book at Pearson and decided that I should just purchase just the access code without the textbook or any e-text. I clicked on the button that said “digital options” but I noticed that the ISBN of the e-text, e-text+access code, access code without e-text are different but they all are the same book, from the same author, in the same edition.

Since it was given as one of the digital options aside from having the actual textbook, i assumed they have the same content inside but it being online would be a reason to change the ISBN number for it. Are there anyone who knows if it is normal to have a different ISBN if you purchase just the access code separately from the textbook?

And just so you guys know, I’m not slacking by not purchasing my books. We’ve just been financially struggling up in here and my parents thought that if I find myself doing okay without books then we should just avoid buying books for the semester to save money.