7th generation iPod from Apple Store or 6G from eBay

[araje]

Hi all, I have an iPad and an iPhone, but never really used an iPod any time. I am planning to buy one for my mom. Question : will either of the above have specific apps for their form factors ?
Can they use iTunes Match ?

I know the spec difference between them but I don't know if their sound quality is just the same or one is better than the other.

I felt the form factor of 6th gen is better suited for my mom.

Let me know if there is anything I need to know about 6th gen that I am ignoring.