New Desktop Computer and SSD Drive

[colin]

I very recently bought a new desktop computer which came with a 500GB SSD drive and a mate of mine installed Ubuntu GNOME 17.10 on it (which i'm not very happy with). But only a couple of days ago i decided to run a "live" cd, Ubuntu MATE. My new desktop has an external CD/DVD drive and i selected this drive in order to run the "live" cd. After i had run the live cd i wanted to change the boot order in the bios back to what it was originally but there are two entries for the ssd drive and i just wonder if i have choosen the wrong one? The entries are:

a) ubuntu (PO: CT500MX500SSD1)
b) PO: CT500MX500SSD1

Would it make a difference if i choose either one?

Also, my mate installed the OS on the SSD drive.
But i would like to know if would it be possible to install an internal 1TB SATA hard drive
So that i could keep the SSD drive just for the OS + updates and everything else would
go on the internal sata hard drive. Hope i'm making sense here lol. 

Thanks all